''A New Map of Texas Oregon and California with the Regions Adjoining. Compiled from the most recent authorities.'' By cartographer Samuel Augustus Mitchell, published in 1846 as a pocket map, and considered the definitive map for settlers in the nation's westward expansion during the Gold Rush. Philadelphia: Published by S. Augustus Mitchell, 1846. With contemporary hand-coloring, folding map by engraver H.N. Burroughs was Mitchell's most important map, considered the defacto standard and thereby affecting subsequent maps of the area. It was the first to include recent explorations in the Great Basin, with boundary lines of Rio Grande to the south, and Oregon to the north at 54 degrees 40 minutes, above which are ''British Possessions''. An inset to lower left entitled ''Emigrant Route from Missouri to Oregon'', provides the distance between western cities and landmarks, undoubtedly aiding weary travelers. With decorative scrollwork along the margins, map measures 21'' x 22.5'' unfolded, nicely matted and framed to a size of 34.5'' x 41.5''. Some expert repair at fold separations and mild fading, overall in very good condition.