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 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.