11. Schedule of mail routes, no. 597, June 1, 1951, 9th division, Postal Transportation Service comprising lower peninsula of Michigan, main line of New York Central R. R. between New York, N. Y. and Chicago, Ill., and collateral lines that may be designated. Bookmark Corporate/Agency Authors: Transportation Bureau and Post Office Dept. Publisher: Transportation Bureau Date: [June 1, 1951.] SuDoc number: P 10.12/9:597