1. Post route map of Porto Rico : showing post offices with the intermediate distances on mail routes Creator: United States. Post Office Dept Published / Created: 1910 Call Number: 856gmd 1910 Container / Volume: BRBL_00643 Image Count: 1 Resource Type: Maps, Atlases & Globes Found in: Beinecke Rare Book and Manuscript Library > Post route map of Porto Rico : showing post offices with the intermediate distances on mail routes in operation on the 1st of December 1910 / published by order of Postmaster General Frank H. Hitchcock.