| Texas
Highways Primer |
|
| This page
last updated November 29, 2012 |
Texas is a big
place. It's nearly 880 miles from the Louisiana border near
Orange to the New Mexico border near El Paso, and nearly 500 miles from
the Oklahoma border north of Dallas to the Mexican border in
Laredo. That size gives the state a tremendous amount of
diversity. A hot, humid sub-tropical climate in the Valley yields
to a varying Midwest climate, complete with snow, in Amarillo.
There are Piney Woods in East Texas, desert in West Texas, and plains,
prairies, and the Hill Country in between. The state has some of
the nation's biggest metropolitan areas and some of its most desolate
ranges. With this size and diversity, a large and rapidly growing
population, a booming economy, an increasing role in international
trade, and its overwhelming dependence on the automobile, Texas cannot
help but have the nation's biggest, most well-developed highway system
with nearly 80,000 miles of state-maintained roads.
This primer is
designed to give you an overview of the state's highway system and its
idiosyncrasies. If you're looking for a route log, check out
Texas Highway
Routes by David Stanek, a complete listing of all highways in
Texas. Both Ron Jackson's TexasFreeway.com and
Andy Field's LoneStarRoads sites have
lots of in-depth information on freeways and other highways statewide.
On this page:
Some
Texas highway facts
Highways in Texas
are managed by the Texas Department of Transportation (TxDOT).
TxDOT was created in 1991 from the former State Department of Highways
and Public Transportation (SDHPT). Here are some facts about the
highway system in Texas:
CENTERLINE MILES
(2010) |
 |
3,233 |
 |
12,105 |
 |
16,336 |
 |
40,939 |
 |
340 |
| Frontage
Roads |
7,041 |
| TOTAL
MILEAGE |
79,994 |
| TOTAL LANE MILES |
193,926 |
- REST AREAS:
92
- PICNIC
AREAS: 615
- FIRST
HIGHWAY: Started in 1918 and finished in 1920, between Falfurrias
and Encino in Brooks County, along present day US 281.
- FIRST
INTERSTATE: 1956, I-45 (then US 75) near Corsicana in Navarro County
- SHORTEST
HIGHWAY: Loop 168 in Tenaha, Shelby County, is 391 feet (.074
miles)
- LONGEST
HIGHWAY: US 83 stretches 899 miles from the Oklahoma state line
near Perryton to the Mexican border near Brownsville
- HIGHEST
HIGHWAY: A spur from Texas 118 at the McDonald Observatory on Mt.
Locke in West Texas is 6,791 feet above sea level.
- BUSIEST
HIGHWAY: I-10/Katy Freeway in Houston just west of Beltway 8
carries 328,000 vehicles daily.
- LONGEST
BRIDGE: The Queen Isabella Causeway between Port Isabel and South
Padre Island is 2.37 miles long.
- NUMBER OF
BRIDGES: 51,808
State-maintained
highways comprise about 26% of the total roadway mileage in Texas but
carry about 73% of all traffic.
Interstates
In addition to
having the nation's largest highway system overall, Texas also has more
Interstate mileage than any other state. There are 16 different
Interstates in the state:
         
    
The Dallas/Ft.
Worth area has two Interstate anomalies: I-35 is split into I-35E
through Dallas and I-35W through Ft. Worth (one of only two such forks
in the nation), and I-345 is an unsigned extension of I-45 in downtown
Dallas. Another unsigned Interstate, I-110, connects I-10 to the
Mexico border in El Paso.
Interstates in
Texas were generally developed along existing US and State
highways. I-45 replaced US 75, I-35 replaced US 81, and I-40
replaced the famed US 66, to name a few. In urban areas, many
existing expressways were simply re-signed as Interstates. The
first Interstate contract let in Texas was for a segment of I-45 in
Navarro County near Corsicana in 1956. The latest addition
to Texas' Interstate inventory is I-69. (See the I-69 section below.) Prior to that, the
last Interstate to be completed was I-27 between Lubbock and Amarillo
in 1992.
Of the
inter-urban Interstates in Texas, I-35 between San Antonio and
Dallas-Ft. Worth is the busiest. Most of I-35 operates at or
above its capacity. Every traffic counter location between San
Antonio and Hillsboro reported more than 50,000 vehicles per day in
2008. As a result, traffic delays, especially during holiday
periods, are common. Besides increases in passenger vehicles,
truck traffic on I-35 and other Interstates is growing rapidly, mainly
as a result of the North American Free Trade Agreement (NAFTA) and the
General Agreement on Tariffs and Trade (GATT). TxDOT reports that
Interstate traffic has increased every year since 1987. Between
1996 and 1999, passenger vehicle traffic statewide increased 12% while
truck traffic increased 19%, and between 1999 and 2011 truck traffic is
predicted to grow 50-70%. In fact, Texas has the highest volume
of truck traffic in the nation.
All of I-35
between San Antonio and Georgetown is now six lanes or more, and a
bypass tollway (SH 130) from Georgetown to I-10 at Seguin was completed
in 2012. Work continues to upgrade I-35 to six lanes all the way
north to Hillsboro. TxDOT is also participating a $1.5 million
federal study of I-35 from Laredo to Duluth, Minnesota, which aims to
provide comprehensive improvements to the corridor. (More
information on the I-35 corridor between San Antonio and Austin is
available as part my San
Antonio roads pages.)
Exits, entrances, and the ubiquitous frontage roads
As you drive through Texas, you may notice that exits and entrances on
many of our Interstates tend to be more frequent than in other
states. This is the result of the wishes of Dewitt Greer, a
former long-time director of the state highway department. It was
his belief that, given the vastness of the state, Interstates should
not just serve "interstate" traffic, but also "interregional" traffic
within Texas, and more frequent exits would help facilitate that.
Another
byproduct of this philosophy is perhaps the most unique feature of the
state's highway system: frontage roads. There are over 7,000
miles of these along freeways in Texas, more-- much more-- than any
other state. The reason for the widespread use of frontage roads
in Texas again can be traced to Dewitt Greer. He decided that it
was cheaper to build frontage roads to keep access to adjacent
properties than it was to purchase those access rights, which is
required under state law. This quickly became standard operating
procedure at the Highway Department (and subsequently TxDOT) and nearly
all of the state's freeways were built under this policy. In June
2001, the Texas Transportation Commission considered a major policy
change that would've rocked TxDOT and Texans in general to the core--
frontage roads would not be included in any new freeways unless
absolutely necessary. This was a fundamental change and caused
quite a stir around the state-- enough of one that the Commission
decided, after statewide hearings, to scrap the idea.
There are
several ramp configurations used with frontage roads. The
"diamond" interchange is pretty standard, with the on- and off-ramps
connecting to the frontage roads in the general shape of a diamond
relative to the cross street (see illustration below). Sometimes,
especially in urban areas, the ramps are reversed in an "X"-interchange
with the exit ramp for the next cross street preceding the entrance
ramp from the previous cross street. This provdes better access
to frontage properties between the intersecting roads and helps reduce
through traffic loads on the frontage roads at intersections.
Occasionally, if space is limited, both the on and off ramps are
built at the same location in a "braided" arrangement (i.e. one ramp
passes-over the other).
Frontage
roads with diamond interchanges |
|
Frontage
roads with "X" interchanges |
Speed limits on
frontage roads generally range from 50-60 mph in rural areas to 40-50
mph in urban areas. In urban areas, access roads are one-way in
the same direction as the adjacent freeway lanes. In rural areas
they are generally two-way. On the frontage road, traffic leaving
or entering the freeway has the right-of-way. Yield signs are
usually posted, but in many areas they're lacking. Many drivers
don't realize that even if there's no sign, they're still required to
yield.
Our ubiquitous
frontage roads are an oddity unique to Texas. However, within
Texas, frontage roads have their own oddity. If you travel
through the state, you may notice that people in each of the major
cities call their frontage roads something different: in Houston,
they're "feeder" roads; in Dallas-Ft. Worth, they're "service" roads;
in San Antonio, they're "access" roads. I've heard that they're
known as "gateways" in El Paso. The term generally used in Austin
and the state's official term is "frontage" road, which is how you'll
see them marked on guide signs statewide, even in the aforementioned
areas where the popular vernacular differ. You can often tell
what part of the state someone hails from just by asking them what they
call that road next to the freeway.
It should be
noted that frontage roads (or whatever you call them) are not just
found on Interstates-- the freeway segments of most US and state
highways also feature frontage roads.
Texans are
frequently surprised when they go to other places and find no frontage
roads. I often hear folks talk about their trips to
(fill-in-the-blank) and one comment that often comes-up is, "They don't
have frontage roads on their highways!" Most native Texans don't
realize how much of an oddity our extensive frontage roads are.
Conversely, many out-of-state visitors immediately notice and comment
on our frontage roads. It's usually about 50/50 between thumbs-up
and thumbs-down.
 Going hand-in-hand with frontage roads are
"turnarounds". These are separate U-turn ramps that allow traffic
heading in one direction on a one-way frontage road to "turn around"
and head the other way on the opposite frontage road without having to
traverse the two frontage road/cross street intersections (see diagram
below). This greatly eases congestion in the intersections.
Turnarounds can run underneath the freeway using the same underpass as
the cross street, or they can cross over the freeway on the same
overpass as the intersecting street or on separate overpasses.  Turnarounds are only used on one-way
frontage roads and therefore are generally found only in urban
areas. Like frontage roads, these may have different names in
different parts of the state. "Turnaround" is the term in San
Antonio, and it's the only place that actually uses "Turnaround" signs,
although the "U-turn ONLY" sign found in most of the rest of the state
is starting to make an appearance there. Other terms used for
turnarounds are "U-turn lane" and "crossover", although the later more
correctly describes an opening in the median on a divided highway.
Turnaround diagram
Typical turnaround in San Antonio
"IH"
Another semantic idiosyncrasy is how TxDOT abbreviates
"Interstate". In most other states, it's I-35, I-10, etc.
Here, TxDOT's official term is "IH", as in IH-35 or IH-10. Of
course, "IH" is short for "Interstate Highway". Furthermore,
depending which part of the state you're in, you may find lots of
people on the street using it, too. (As you can tell by my pages,
I prefer "I" myself.) I guess TxDOT likes "IH" because all of
their other highway abbreviations are two letters as well.
Interstate 69
 With the growth of NAFTA traffic, Texas began making plans
for a new Interstate, I-69, between Texarkana and Laredo, and "Future
I-69" signs began appearing on US 59 in the Houston area in 2000.
I-69 will replace the existing US 59, one of several corridors being
strained by burgeoning NAFTA traffic. As originally envisioned,
one or two spur routes along US 77 and US 281 will connect this route
to the Lower Rio Grande Valley (Brownsville-McAllen-Edinburg
area). During the first decade of this century, planning for this
route was rolled-into the Trans-Texas Corridor as "TTC-69" (more
details on the TTC below.) However,
after the demise of the TTC, the I-69 project was continued as a
standalone effort.
In August 2011,
the Federal Highway Administration approved Texas' request to sign the
first section of I-69 in the state. In December 2011, signs went
up on a 6.2 mile section of the US 77 expressway between I-37 and
Robstown just west of Corpus Christi. In September 2012, 35 miles
of US 59 stretching from Loop 610 in northeast Houston to the
Montgomery/Liberty county line was also signed as I-69.
About 200 additional miles are expected to be signed in 2013.
More information on I-69 in Texas is available at the Alliance for I-69 Texas
website.
Interstate 27 extension
TxDOT commissioned a study during the early '90s to investigate
extending I-27 south from Lubbock. Three corridors were
considered: US 87/SH 349 to Midland, a Sweetwater-San Angelo-Junction
corridor connecting to I-10, and another corridor through Big Spring to
I-10 at Ozona. The I-20 to I-10 segments of these corridors were
studied separately. The study concluded that there was not enough
traffic, present or projected, to warrant an extension of the
Interstate for the foreseeable future. Instead, a package of
upgrades to US 385, SH 349, US 87, and US 84 was recommended.
With the
passage of NAFTA, additional studies have been done on this
"Ports-to-Plains" corridor. You can read more about it at Andy
Field's AARoads
website and at the Ports-to-Plains coalition
website. Once again, projected traffic volumes were determined to
not be sufficient for an Interstate in this corridor. Instead,
various options including bypasses, intersection improvements,
additional lanes on existing roads, and ITS measures were recommended.
Exit numbers
Texas, like most states, switched from a sequential exit numbering
system to a milepost numbering system in the mid to late '70s and early
'80s. The exit number is typically posted at a tab on top of the
exit gore sign, but starting in 2012, signs with the exit number
incorporated in the main sign panel began appearing.
State
highways
 |
The State
Highway system includes State Highways (SH), Loops (LP), and Spurs
(SP). There are also Park Roads and Business Routes. There
are a few "special" state highway designations as well: OSR (Old San
Antonio Road) near Bryan, NASA Road 1 leading to the Johnson Space
Center, and Beltway 8 around Houston. |
"Loop"
A term you are sure to hear across the state is "Loop".
Even when they're Interstates, you'll usually hear beltways and other
bypasses referred to as "Loop" such-and-such. For example,
I-410 around San Antonio is usually called "Loop 410" and I-610 in
Houston is known simply as "The Loop" (usually with the location
inserted, e.g. "the West Loop.") However, there is an official
state highway designation of "Loop (LP)". This category includes
many routes that are not circular or even a bypass! Short state
highways whose main purpose is to connect two or more highways are
usually designated as a Loop. A good example is Loop 1 (MoPac
Expressway) in Austin. It is basically straight and runs pretty
much through the heart of the city, but it connects several US, SH, and
FM routes along the way.
Business Routes
 Prior to 1991, all business routes
carried an internal arbitrary State Highway Spur or Loop designation,
although in most cases they were actually marked with the business
route sign for the parent route from which they branched. In
1991, those internal designations were dropped and the business route
designations were made official.
How Texas marks
business routes is unique. Firstly, TxDOT often puts a small
letter at the bottom of most business route shields. This letter
indicates which branch in the series for the parent highway that
particular segment is. For example, US 90 passes through several
towns. The business route through the first town would be labeled
"A", the one through the next town labeled "B", and so on, although
this practice isn't followed rigorously throughout the state.
Secondly, on US business routes, TxDOT often does not use the "BUS" or
"BUSINESS" auxiliary plate mounted above the US route marker.
Rather, the word "BUSINESS" is included within the US shield above the
number, as shown to the right.
 |
Interstate
Business Loops were fairly rare in Texas until the state decommissioned
all US highways that were completely coexistent with Interstates in
1991. Along those Interstates, the US route had previously
provided the parent route for the business routes. Those have
since been replaced with Interstate Business Loops. |
Park roads
The state also has about 88 Park Roads and Recreation Roads,
which provide access to state and national parks and other designated
recreational areas. TxDOT also maintains all roads within state
parks, though they are not marked state routes.
Farm-to-market
roads
 More than half of the
state's highway system is comprised of the Farm-to-Market (FM) road
system, which also includes Ranch-to-Market (RM) roads. Although
the first FM road opened in 1937, the system really grew after the 1949
Legislature set aside $15 million annually from the state's General
Fund for their construction. General Fund money is no longer
used, but the FM system is still paid for entirely by the state.
The FM system is the most extensively developed rural highway system in
the nation. Its nearly 41,000 miles is more than double the
entire state highway mileage of the six New England states combined.
Although the
FM/RM route sign reads "Farm Road" or "Ranch Road", the routes are
officially designated as "farm-to-market" or "ranch-to-market".
Larger guide signs do mark the routes as "FM" and "RM" (see the "signs" topic below.) There is only one
route officially designated as "Ranch Road", that being Ranch Road 1
leading up to the LBJ Ranch east of Fredericksburg. There is no
difference between FM and RM roads; just another Texas highway semantic
idiosyncrasy. Routes east of US 281 are generally labeled as FM
roads; those west of US 281 are generally marked as RM roads.
 With the explosive growth of metropolitan areas
in Texas over the years, many FM routes are now in metropolitan
areas. Houston and San Antonio in particular have a large number
of FM roads within their urban areas. One could drive many of
these routes and never see a farm or ranch, much less anything being
transported to market. Still, only about 4% of the total FM
mileage is within urban areas. Since the FM system is entirely
state-funded, an effort was made in 1995 to create a new classification
for FM routes in urban areas called "Urban Roads" to enable them to
receive federal funding. The proposed sign would be the simple
state highway square with the word "urban" and the route number.
An outcry from the public about the changing the familiar Texas-shaped
sign stopped the plan to re-sign the roads, but TxDOT's internal
highway designation logs were changed to re-classify FM roads in
metro areas as Urban Roads. In 2012, there were 252 roadway
segments classified as UR.
Prior to the
Urban Road system, TxDOT created a classification of roadway in 1988
called the Principle Arterial Street System, or PASS (designated as PA
routes.) This classification allowed for existing and new major
urban arterials that provide access to or relief for major
state corridors (typically freeways) to receive matching state and
federal funding without being officially signed as state roadways.
Due to financial constraints, the PASS program was
essentially discontinued in 1992 and is slowly being sunsetted with the
190 roadway segements included in the PASS system being funded as
resources become available or transitioned to other funding
categories.
Innovation
Texas has
always been on the leading edge of highway technology. The Texas
Transportation Institute (TTI) at Texas A&M University has
spearheaded much of this highway research. Here are some of the
many innovations to come from Texas:
- The "Texas
Twist" guardrail end was developed in the 1970s to deflect vehicles by
burying the ends of the guardrails. As cars got smaller, though,
many flipped when hitting this. So in the late '80s and early
'90s, TTI developed a new guardrail end treatment called the
ET2000. This new guardrail end absorbs the impact of a vehicle by
extruding the rail and breaking the wooden posts.
- Texas
initiated the concept of roadside parks. The first picnic area
opened in 1933 along Texas 71 between Smithville and La Grange.
In recent years, though, funding issues, as well as the proliferation
of fast-food restaurants, has resulted in Texas closing an increasing
number of picnic and rest areas, especially near urban areas.
- The
"adopt-a-highway" project was developed in Texas and it was the first
state to implement it statewide. More than 45 other states have
since emulated this program. There are currently about 3,800
groups collecting litter along 8,000 miles of highway. It is
estimated that this program saves the state $2.5 million a year in
litter clean-up costs.
- Breakaway sign
posts and streetlights were developed in a two-year program to reduce
the seriousness of roadside object impact accidents.
 After
125 crashes resulted in not one single injury, the federal government
mandated their use on all federally-funded roads. Texas
also developed the breakaway "coat hanger" rural mailbox support,
which was recently redesigned.
- A modified
version of the standard Jersey-barrier designed to reduce the
likelihood of smaller vehicles flipping over on impact was developed in
the 1980s by TTI. TTI also designed a special heavy-duty
extra-tall guardrail for a downtown San Antonio freeway ramp to prevent
heavy trucks from crashing down onto a high school football
field. To test it, they crashed a fully-loaded tanker truck into
it! This rail design has since been used in many other locales
where extra strength crash-barriers are needed.
Don't
Mess With Texas™
During the mid
'80s, the forerunner of TxDOT introduced what would become an
incredibly popular anti-litter campaign. "Don't Mess With Texas"
signs went up around the state. The slogan took off, and now you
can get "Don't Mess With Texas" T-shirts, mugs, stickers, keychains,
hats... you get the idea. There have also been numerous "Don't
Mess With Texas" commercials featuring various celebrities. In
2005, TxDOT began cracking-down on unauthorized use of the slogan and
logo.
ITS
With freeways in
many areas reaching their maximum width, the Texas Transportation
Commission in 1989 committed to building Intelligent Transportation
Systems (ITS) in the state's largest metro areas. The first
system to go online was TransGuide in San Antonio, which at the time
was the first advanced metro freeway ITS system in the nation.
TransStar in Houston followed shortly thereafter. Most of the
state's largest metro areas now have ITS systems, and it has been
expanded to several busy rural corridors as well. These systems
use a various technologies to monitor traffic conditions and warn
drivers of problems.
Signs
Texas has more
road signs than any other state. There are over 500,000 signs on state
maintained highways.
Texas is probably
the only state that has two different versions of our highway
markers. One version is the freestanding sign, and the other is
for use on freeway guide signs. Here are some examples:
| STANDALONE
SHIELDS |
|
GUIDE SIGN SHIELDS |
| |
|
 |
| |
|
 |
| |
|
 |
After
World War II, the route marker for state highways was changed to
today's boring square. Prior to then, the shield featured the much more
unique circle and five-point star design shown at the left. |
Toll
roads
 Until the early 2000s, Texas law prevented the state from
building or operating toll highways. Instead, they could be built
and operated by subsidiaries of TxDOT or independent agencies created
specifically for that purpose. For instance, the Texas Turnpike
Authority built and operated tollways in the Dallas area, including the
Dallas-Ft. Worth Turnpike, which was the state's first toll road.
North Texas tollways are now operated by North Texas Tollway Authority
while the Harris County Toll Authority built and operates several
tollways in the Houston area (see sidebar below). In the late
'90s, a private toll road, the Camino Columbia, was built to connect
the Columbia Solidarity Bridge northwest of Laredo to I-35. Due
to a lack of traffic caused by federal delays to implementing the North
American Free Trade Agreement (NAFTA), that road eventually was sold to
the state and is now operated by TxDOT. In recent years, with
worsening congestion and insufficient funding from the state
legislature, the state has been advocating toll roads as a viable
option to get new roads built and several new tolling agencies have
been created around the state. Perhaps the most controvercial
toll road proposal was the statewide Trans-Texas Corridor project (see below).
 |
The Sam Houston Tollway around Houston is also signed as
Beltway 8, a state highway. However, because of the previous
restriction of not allowing state highways to be toll roads, only the
frontage roads along the toll route are actually Beltway 8. The
tolled mainlanes are just the "Sam Houston Tollway", operated by the
Harris County Toll Road Authority. |
Trans-Texas Corridor
 In 2002, Texas Governor
Rick Perry announced a concept for a massive new transportation system
in Texas. The plan, called the "Trans-Texas Corridor" (TTC), was
subsequently approved by the legislature and called for 4,000 miles of
superhighway/rail/utility corridors crisscrossing the state. As
envisioned, each corridor would have been 1,200 feet wide and include
separate roadways for passenger vehicles and trucks, separate tracks
for freight and passenger rail, and a right-of-way for utilities such
as gas, oil, and water pipelines and electrical transmission and
telecommunications lines. Specifically, here's how a typical
corridor would have been divvied up:
- Four truck
lanes, four each way (A on the diagram below)
- Six passenger
vehicle lanes, three each way (B)
- Two sets of
tracks for high-speed passenger rail, with stations (C)
- Two sets of
tracks for freight rail (D)
- Two sets of
tracks for commuter rail, with stations (E)
- A utility
corridor about 200 feet wide (F)
- Maintenance,
safety, and expansion zones as necessary
Trans-Texas Corridor typical cross-section
(Letters correspond to descriptions above)
The
roadways would have had limited interchanges with exits only at
intersections with other TTC routes, Interstates, US, and major state
and FM highways. It was planned that the passenger roadways would
have speed limits of 80mph. The corridors would have been
developed and operated by private companies under a state
franchise. These companies would charge tolls and fees for
users.
There
were four priority corridors:
- TTC-35, to
parallel or overlap I-35 from Denison to Laredo
- TTC-69/future
I-69, from Texarkana to Laredo via Houston, with branches to the Lower
Rio Grande Valley
- I-45 from
Dallas to Houston
- I-10 from El
Paso to Orange
The
project, however, met with fierce opposition, especially in rural areas
as the wide corridors would have taken many acres of farming and ranch
lands. Furthermore, there was a general discontent with the
concept of having the roads operated by private companies, especially
ones with foreign ties. As a result, the project was killed by
the Legislature in 2009. The TTC-35 and TTC-69 projects, which
were in advanced planning at the time, continued but not under the TTC
brand. The TTC-35 project was also eventually canceled (although
the SH 130 segment from Georgetown to Seguin was allowed to be
completed as a regional project), but planning for TTC-69 (the I-69
extension) continues as its own project (see I-69
above.)
Tunnels
& ferries
TxDOT operates
two ferry services. The longest is on SH 87 from northern
Galveston to Port Bolivar. Another short ferry connects Port
Aransas and Aransas Pass on SH 361. The Harris County Toll Road
Authority studied a possible bridge to replace the Galveston-Bolivar
ferry, but determined it to not be feasible. Harris County also
operates the Lynchburg Ferry east of Houston near San Jacinto State
Park.
There are
currently no tunnels on the state highway system. At one time,
TxDOT did operate a tunnel under the Houston Ship Channel on SH 146
between La Porte and Baytown. It was replaced in the early '90s
by the impressive cable-stayed Hartman Bridge. There are, however,
three road tunnels in Texas that are not part of the state highway
system: the Washburn Tunnel, which is also under the Houston Ship
Channel on Federal Road; the Addison Airport Toll Tunnel in Addison
north of Dallas (operated by NTTA); and one in Big Bend National Park.
Other sites of interest
|
Texas highways primer
