Most of the Post Office works of art were funded through commissions under the Treasury Department's Section of Painting and Sculpture (later known as The Section of Fine Arts) and not the WPA.

"Often mistaken for WPA art, post office murals were actually executed by artists working for the Section of Fine Arts. Commonly known as "the Section," it was established in 1934 and administered by the Procurement Division of the Treasury Department. Headed by Edward Bruce, a former lawyer, businessman, and artist, the Section's main function was to select art of high quality to decorate public buildings if the funding was available. By providing decoration in public buildings, the art was made accessible to all people." from "Articles from EnRoute : Off The Wall: New Deal Post Office Murals" by Patricia Raynor

Unless indicated, works of art are located in the US Post Office building.

Certainly one of the more exotic locations for New Deal/WPA art is the US Post Office in Charlotte Amalie, US Virgin Islands.
	There are two murals installed in the lobby, both done by Stevan Dohanos in 1941.
"The Virgin Islands, U.S. - The Outer World Significance"
and "The Virgin Islands, U.S. - The Leisurely Native Tempo". Both are still extant and on public display.

Source:
Democratic Vistas: Post Offices and Public Art in the New Deal
by Marlene Park & Gerald E. Markowitz