The U.S. Post Office in Pearl River, New York, is located at the junction of Franklin and Main streets in the hamlet's downtown. It is a brick building from the mid-1930s, serving the ZIP Code 10965, which covers the hamlet of Pearl River. Its design, an application of the Colonial Revival architectural style commonly used for post offices of that era, is unique to it. It shows a strong modernist influence, with almost no ornament on its exterior, and no public art inside.