Josiah Gregg's monumental map of Northern Texas & the Plains, which accompanied his Commerce Of The Prairies (Wagner-Camp 108), one of the Classic Accounts of the Transmississippi West and a cornerstone work for studies of the Santa Fe Trail. Wheat refers to the map as a cartographic landmark and is book as the most important work on the Southwest to date. Gregg was a Santa Fe Trade. Based upon Humboldt's map of New Spain, Long's 1st Expedition and JC Brown's survey's along the Santa Fe Trail, with corrections added by Gregg from observations. Shows nearly a dozen major routes of commerce and exploration during the period. Wheat devotes 2 pages to its description (Wheat 482). A nice example from Morse & Breese's Cerographic Atlas of 1844.