The map shows in detail the western portion of the U.S. to the Pacific, Oregon as claimed by the United States and the whole of Upper California with the Indian Territory, Missouri Territory, Iowa, and portions of the states of Missouri, Arkansas, Louisiana, and Wisconsin as well as northern Mexico and part of British Columbia, illustrating in detail the trans-Mississippi region at a time when war was imminent with Mexico.
Great attention has been given to Texas which shows as its southern border the Rio Grande. Both the Santa Fe and the Oregon Trails are detailed and have a table of distances printed in the lower corner of the map. Oregon is shown as extending to 54° 40 minutes.
The map is issued with the Accompaniment to Mitchell's New Map of Texas, Oregon, and California, with the Regions Adjoining. As noted in the Accompaniment, "Texas has recently become part of the United States, and California is simply, ""Upper California. This part of Mexico was declared independent in 1845. It has of late attracted much attention in the United States; a number of Americans are already settled in it, and many others are preparing to emigrate thither.."" Regarding Oregon, the Accompaniment declares that ""the United States have an indubitable claim to the whole region of Oregon, from N. latitude 42° to 54° 40', yet the government has several times proposed, from motives of accommodation, to adopt the 49th parallel of latitude as the dividing line.."" . Wheat describes the map: ""In the Upper California portion, Fremont is carefully followed, while further north Wilkes is followed. The boundary (to be) with Mexico is imperfectly shown but Texas appears with the magnified boundaries, including Santa Fe, of the 1844 Emory. The various claims to Oregon appear. The Accompaniment is of particular interest, containing perhaps the clearest statement of Oregon and California facts that came out of the period just prior to settlement of the former's boundaries and inclusion of the latter in the United States.""
The text describes each state and territory in turn and references early explorers as well as Lewis and Clark, historical persons and events. In the advertisements at the end of the text, Mitchell declares: "This Map represents that part of North American which extends from lat. 26 to lat. 56 N., and from the Mississippi River to the Pacific Ocean. [Graff 2841. Howes M685. Martin & Martin 36. Wagner-Camp 122b. Cowan p. 433. Wheat Transmississippi 520. Phillips Maps p. 844. Wheat Gold Regions 29].