Thomas, Cowperthwait & Co.Washington prime meridian. "Entered according to Act of Congress, in the year 1850, by Thomas, Cowperthwait & Co., in the clerks Office of the District Court of the Eastern District of Pennsylvania." Includes list of steam boat routes with distances. 30. in upper right margin. Inset: Western part of michigan [ca. 1:3,000,000].34 x 27 centimetersJPEGUMN_ALMA:9973519737701701engThomas, Cowperthwait & Co. (Philadelphia), 1850PublicA new map of Michigan with its canals, roads & distancesMapsMichigan1850University of Minnesota