Walker's research is concerned with the importance of wagon freighting in the economic development of the American West. The time period under discussion begins in 1822, with early merchandise wagons making the trip from Franklin, Missouri to Santa Fe, New Mexico. It concludes in 1880, when the railroad system reaches the mining towns of Montana. Some illustrations are reproduced from historic photographs. Maps show principal routes of both water and land commerce. Charts and graphs follow the extensive bibliography. Some show the number of wagons by year, while others depict comparative prices of wool and grocery items such as coffee, bacon, sugar and flour.