The Texas state highway system is the network of roads built, maintained, and regulated by the Texas Department of Transportation under the direction of the Texas Transportation Commission. It covers roughly 81,180 centerline miles and more than 201,000 lane miles, making it one of the largest state-managed road networks in the country.1Texas Department of Transportation. 2024 Roadway Inventory Report The system is paid for through a mix of state fuel and registration taxes, federal highway dollars, and two voter-approved transfers from oil, gas, and sales tax revenue, all protected by the Texas Constitution from being spent on anything other than public roads.
What Counts as a State Highway in Texas
Four classifications of road sit inside the on-system inventory, each with its own route marker and role.
- Interstate Highways carry the red, white, and blue shield. Odd numbers run north-south, even numbers east-west.2Federal Highway Administration. Interstate System
- U.S. Highways use a white shield on a black background and predate the Interstate system.3Federal Highway Administration. Manual on Uniform Traffic Control Devices – Figure 2D-3 Long Description
- State Highways carry the Texas-shaped shield and serve as the main connectors within state borders.4Texas Department of Transportation. Sign Crew Field Book – Route Signs
- Farm to Market (FM) and Ranch to Market (RM) roads are a Texas original, built in the mid-twentieth century to connect agricultural producers to distribution hubs.
FM designations are generally found east of the Colorado River; RM designations appear in western ranching country. The label reflects the dominant land use at the time of designation, not necessarily what the road passes through today. Suburban growth has turned many former two-lane farm connectors into busy commuter routes, but their legal status has not changed. FM and RM roads carry the same standing as any other state highway, which means TxDOT is responsible for their construction, maintenance, and reconstruction.5State of Texas. Texas Transportation Code 201-104
The Transportation Commission can also pull county roads into the state system. When a county commissioners court agrees to waive claims for state participation in any existing road debt, the commission can convert the county road into a farm-to-market road and the state takes over construction and maintenance from that point forward.5State of Texas. Texas Transportation Code 201-104
Who Runs the System
TxDOT operates under the Texas Transportation Commission, a five-member body appointed by the governor. The commission adopts the rules governing the department, selects construction projects, sets engineering and safety standards, keeps the official records and road plans, and manages the budget for the entire state highway system. It also holds statutory authority to designate new highways, remove segments no longer needed, and consider turnpikes built by other entities for incorporation into the network.
Jurisdiction gets more complicated when a state highway runs through a city. Designating a road as part of the state system generally transfers primary maintenance responsibility to TxDOT, even when the road doubles as a city street. The state handles the travel lanes and structural pavement; the municipality typically manages adjacent sidewalks, street lighting, and drainage outside the roadway itself. These divisions are usually spelled out in formal agreements between TxDOT and local governments. The split matters for liability: a pothole on a state-designated highway is generally the state’s problem, not the city’s. Local ordinances cannot override state rules on these routes, so cities cannot unilaterally change speed limits or access rules on roads TxDOT controls.
How the System Is Paid For
Highway money flows into the State Highway Fund, officially designated Fund 0006.6Texas Comptroller of Public Accounts. Fund 0006 – State Highway Fund Several revenue streams feed it.
Motor Fuels Tax
Texas charges 20 cents per gallon on both gasoline and diesel. The rate has not changed since 1991, so inflation has steadily eroded its real purchasing power.7Texas Comptroller of Public Accounts. Texas Motor Fuels Taxes Not all of it goes to roads. The Texas Constitution directs one-fourth of net motor fuel tax revenue to the Available School Fund.8Justia. Texas Constitution Article 8 – Section 7-a
Vehicle Registration Fees
The base annual registration fee for a standard passenger car or light truck weighing 6,000 pounds or less is $50.75, with county fees added on top.9Texas Department of Motor Vehicles. Schedule of Texas Registration Fees Heavier commercial vehicles pay progressively more. The revenue goes into the State Highway Fund.
Federal Contributions
The federal government collects 18.4 cents per gallon on gasoline and 24.4 cents on diesel, which flows into the federal Highway Trust Fund.10U.S. Energy Information Administration. How Much Tax Do We Pay on a Gallon of Gasoline and on a Gallon of Diesel Fuel Texas gets its share back through a formula that guarantees each state at least 95 cents for every dollar its motorists contribute. Under the Infrastructure Investment and Jobs Act, each state’s annual apportionment must also run at least 1% above the prior year.11Federal Highway Administration. Apportionment
Proposition 1 and Proposition 7
Voters added two constitutional funding streams when fuel taxes and registration fees stopped keeping up with growth. Proposition 1, approved in 2014 by 80% of voters, directs a portion of oil and gas severance tax collections above a preset threshold (tied to 1987 production tax levels) into the State Highway Fund, with the balance split evenly between the fund and the Economic Stabilization Fund. For fiscal year 2026, the deposits total roughly $2.52 billion, and cumulative transfers since the amendment took effect exceed $21.6 billion. The legislature has extended Proposition 1 transfers through December 31, 2042.12Texas Department of Transportation. Proposition 1 Funding
Proposition 7, approved in 2015, added two more streams: up to $2.5 billion in state sales tax revenue above a $28 billion annual threshold, plus 35% of motor vehicle sales tax revenue above $5 billion per year. Both Proposition 1 and Proposition 7 money carries a key restriction: it can only be spent on building, maintaining, or acquiring rights-of-way for public roads, and never on toll roads.
Constitutional Protection
Article VIII, Section 7-a of the Texas Constitution requires that net revenues from motor vehicle registration fees and motor fuel taxes be used only for acquiring rights-of-way, building and maintaining public roads, policing those roads, and administering related traffic safety laws.8Justia. Texas Constitution Article 8 – Section 7-a The practical effect is that the legislature cannot pull money out of the highway fund to patch other budget holes. Combined with the dedicated Proposition 1 and 7 flows, this creates a relatively stable funding base. The 25% school fund allocation remains the one carve-out.
Toll Roads as a Separate Track
Toll roads sit outside the standard tax-and-appropriate model. Texas law authorizes both TxDOT and independent regional tollway authorities to plan, build, and operate toll facilities. Regional authorities can acquire property, issue bonds, set and adjust toll rates, and adopt rules governing use of their roads.13State of Texas. Texas Transportation Code Chapter 366 They can require electronic transponders, use video tolling, and contract out collection. Toll rates must cover maintenance, operations, and bond debt, and no other state agency can regulate them. Toll projects find their own financing, usually through revenue bonds backed by projected collections, because Proposition 1 and 7 money is off-limits to them.
Rules That Govern the Road
Speed Limits
Texas sets default speed limits by road type. On numbered state and U.S. highways outside urban areas, including FM and RM roads, the default is 70 mph. Unnumbered highways outside urban districts default to 60 mph. Urban streets are capped at 30 mph and alleys at 15 mph. The Transportation Commission and local authorities can post higher or lower limits based on traffic studies and engineering analysis. Segments of State Highway 130, a toll road southeast of Austin, carry the highest posted limit in the country at 85 mph. On rural interstates and divided highways, 75 mph is common.
Overweight Vehicle Penalties
Weight limits protect pavement and bridges, and the fines for exceeding them climb sharply.14State of Texas. Texas Transportation Code Chapter 621
- Under 2,500 lbs overweight: $100 to $500
- 2,500 to 5,000 lbs: $500 to $1,000
- 5,001 to 10,000 lbs: $1,000 to $2,500
- 10,001 to 20,000 lbs: $2,500 to $5,000
- 20,001 to 40,000 lbs: $5,000 to $7,000
- More than 40,000 lbs: $7,000 to $10,000
A third overweight conviction within a single year doubles the applicable fine range. Carriers hauling a divisible load above 84,000 pounds without a permit face an additional $500 to $1,000 penalty on a first offense. These are civil liquidated damages under Texas law, separate from any criminal misdemeanor fine, which is typically capped at $250 for basic weight violations.
Federal Strings Attached
Accepting federal money brings compliance obligations that reach into how Texas plans, builds, and maintains its roads. Any highway project built with federal funds must be properly maintained by the state. If the Federal Highway Administration finds that a federally funded project is not being adequately maintained, it notifies the state, and if the problem is not corrected within 90 days, FHWA can withhold approval of further federal projects in the affected area or statewide.15Office of the Law Revision Counsel. 23 USC 116 – Maintenance
Federally funded projects also go through environmental review under the National Environmental Policy Act. Projects likely to cause significant environmental effects require a full Environmental Impact Statement; projects with uncertain impacts get an Environmental Assessment; minor projects can qualify for a categorical exclusion. Significant projects require at least one public hearing, and draft impact statements go out for a 45-to-60-day public comment period.16eCFR. Environmental Impact and Related Procedures
Highway bridges on the system must be inspected under the National Bridge Inspection Standards at intervals no greater than 24 months, with more frequent inspections for bridges in worse condition and separate schedules for underwater components.17eCFR. National Bridge Inspection Standards Title VI of the Civil Rights Act bars discrimination in federally funded highway programs on the basis of race, color, national origin, or sex, and requires agencies to collect demographic data on affected communities and make Title VI information publicly available.18eCFR. Title VI Program and Related Statutes – Implementation and Review Procedures All roads open to public travel must follow the Manual on Uniform Traffic Control Devices for signs, signals, and pavement markings.19Federal Highway Administration. Manual on Uniform Traffic Control Devices Many Texas state highways are also part of the National Highway System, a federally designated network of principal arterials, Interstate routes, and strategic defense corridors; inclusion brings additional funding eligibility and heightened maintenance and reporting requirements.20eCFR. Highway Systems – 23 CFR Part 470
Right-of-Way and Eminent Domain
Building or widening a highway often requires taking private land. The Transportation Commission can buy property through negotiated sales or, when negotiations fail, use eminent domain to condemn it. The commission can acquire full ownership or a lesser interest, and condemnation proceedings follow the Texas Property Code.
Two carve-outs limit the state’s reach. When condemning land for highway purposes, TxDOT must exclude all oil, gas, and sulfur rights beneath the surface. The mineral owner keeps those rights but loses any right of physical surface access for exploration or drilling. Cemetery property is off-limits to condemnation entirely.