A map of the United States and territories showing the expansion from the formation of the original states to 1880, and the railroad network in 1880. The map is color-coded to show the original states, the states admitted between 1791 and 1860 (including Maine from Massachusetts in 1820), states admitted between 1861 and 1876 (including West Virginia from Virginia in 1863, Nevada, Colorado, Nebraska, and Kansas), territories in 1880 (including Washington, Idaho, Montana, Dakota, Wyoming, Utah, Arizona, New Mexico, and the Indian Territory of Oklahoma), the British possessions in Canada and the Bahamas, and Mexico. The map marks the frontier of the United States by a dashed line, and the railroad network at the time with the Pacific railroads receiving direct federal aid indicated. The map illustrates the problem of transportation to the west of the frontier line at the time, and its significance to the development of the west.