One of the best map collections is at the Texas State Library. A bibliography of over 2,000 maps in this collection is James M. Day, Maps of Texas, 1527-1900: The Map Collection of the Texas State Archives (Austin, Texas: Pemberton Press, 1964; FHL book 976.4 A3d). Other good collections of maps of Texas are available at:
University of Texas at Austin
Austin, TX 78712-7330
University of Texas at El Paso Library
Documents and Maps
El Paso, TX 79968-0582
Southern Methodist University
Central University Libraries
Dallas, TX 75275-0135
The Family History Library has several maps and the following atlases:
Martin, James C., and Robert S. Martin. Maps of Texas and the Southwest, 1513-1900. Albuquerque, New Mexico: University of New Mexico Press, 1984. (FHL book Q 976.4 E7m.) This includes histories of the area and of the maps.
Pool, William C. A Historical Atlas of Texas. Austin, Texas: Encino Press, 1975. (FHL book 976.4 E3p.) This includes maps of Texas during the frontier era, Indian territories, and travel routes.
Printable maps are also available from the National Atlas of the United States -- http://nationalatlas.gov/printable.html