Several types of maps are useful for genealogists. Some give the historical background of the area; others show migration routes such as roads, rivers, and railroads. Topographical maps show physical and manmade features, such as creeks, hills, trails, and roads used as persons came to Oklahoma. Sometimes maps also include cemeteries and churches. Plat and land ownership maps, as well as other types of maps, are described in United States Maps. In the Family History Library Catalog, atlases are listed in the Place Search. Remember to search each locality as a town, a county and as a state.
One of the best books of maps for Oklahoma is John Wesley Morris, Charles R. Goins, and Edwin C. McReynolds, Historical Atlas of Oklahoma, 3rd ed. Norman, Oklahoma: University of Oklahoma Press, 1986. (Family History Library book 976.6 E3m 1986; 1965 edition on film 1000357 item 3.)
United States Census Bureau State and County Map. This map will allow you to zoom in on any state or county in the United States and read the names of all of the neighboring counties.
The Family History Library has several maps, including some of the Indian Territory.
Printable maps are also available from the National Atlas of the United States -- http://nationalatlas.gov/printable.html