The WPA laid or improved over 650,000 miles of roads, built or rebuilt around 78,000 bridges, and constructed roughly 800 airports, deliberately by hand to employ as many idle people as possible. Its showpiece was New York's municipal airport, LaGuardia. The episode scores infrastructure as the WPA's clearest success.
Bridge counts range from over 10,000 to about 78,000 depending on what is counted. Whether the slower, hand-built method was the right trade-off remains argued, and WPA projects were partnerships with local sponsors.