Patch with eagle emblem
The embroidered emblem patch features the United States Postal Service’s eagle seal. The dark blue eagle sits above a red line that serves as the top border for the letters "U.S. MAIL,” which are underlined by a blue bar. Concentric, ochre-colored rings frame the patch’s white background.
The Postal Reorganization Act signed in 1970 brought about significant changes in the postal systems structure. Accordingly, the newly-titled United States Postal Service updated the former Post Office Department’s iconography, including emblems for employee uniforms. City delivery service letter carriers applied this eagle patch to the left side of the following uniform articles: shirt, sweater, and jacket sleeves, as well as the chests of parkas and raincoats.
http://www.usps.com/postalhistory/postal_patchwork.htm (Accessed April 10, 2006)