The Texas Department of Transportation website includes a statewide planning map with a Reference Markers overlay. Selecting the Reference Markers overlay displays the mile markers for state and federal roads in Texas, but does not include mile marker information for local or minor roads. Intervals displayed vary between 1 and 100 miles depending on the zoom level of the map.
The statewide planning map located on TXDOT.gov also provides other information about Texas highways, including overlays showing the state's freight network, the functional classification of each road, the areas managed by each road maintenance office, the vertical clearance of every bridge and overpass, and speed limits. Optionally, switch the map between the Texas DOT's street map, a street map created by Esri, satellite images and a topographic map.
The map also includes information on future projects, including Texas' 10 Year Porgram, Proposition One, candidates for future projects and feasibility studies conducted by the DOT, as of 2016.
The Texas Reference Marker System was created in 1989 in order to provide a common reference key for highway data in the state. The development of the TRM system included locating and digitally recording all of the physical reference markers on Texas highways.