The first post office in the Buchanan County town of Winthrop in 1861 with Abbott E. Dulton as the first postmaster. Postal service was originally established in the town in 1853 under the name of Pine. In addition to mailing services, early post offices stocked a number of goods, with 1881 newspaper ads highlighting a number of available items:

• “A fine line of Bibles and Albums for sale at the post office.”
• “Christmas cards for sale at the post office.”
• The largest assortment of fine candies in town, at the post office.”

After being housed in a number of homes and storefronts, the modern post office facility was constructed on the northeast corner of Madison and 3rd Streets in 1999.