- Post Office - Middleport OHThis post office, completed with funds from the federal government in 1937, is also the site of Clara Fasano's 1939 plaster sculpture, "The Family," completed with funding from the Treasury Section of Fine Arts and located in the post office's lobby.
- Post Office - Midland PAThe historic post office in Midland, Pennsylvania was constructed ca. 1938 with Treasury Department funds. The building, which houses an example of New Deal artwork, is still in service.
- Post Office - Mifflinburg PAThe historic post office building in Mifflinburg, Pennsylvania was constructed with federal Treasury Department funds. The building, which opened in , is still in use today. Striking New Deal artwork resides in the lobby.
- Post Office - Milford NHThe historic post office in Milford, New Hampshire was constructed with federal Treasury Department funds in 1939. The building, which houses an example of New Deal art, is still in use today.
- Post Office - Millburn NJThe historic post office in Millburn, New Jersey was constructed in 1939 with Treasury Department funds. The building, which housed an example of New Deal artwork, is still in service.
- Post Office - Millbury MAThe contract to build the Millbury post office was awarded to the Daniel Cunningham Construction Company on March 15, 1940. The project was to be completed within 270 calendar days at a cost of $54,353.00. Groundbreaking occurred at the end of April and construction was completed in late October. The building officially opened on January 27, 1941 with postmaster James L. Ivory. The walls and ceiling are constructed of steel and are reinforced with stone and concrete. The basement contains a large room that was originally constructed as a bomb shelter. The mural "An Incident in the King Philip War, 1670" was painted...
- Post Office - Millersburg PAThe historic Millersburg post office was constructed with Treasury Department funds between 1935 and 1936. The building is still in service.
- Post Office - Millinocket MEConstructed in 1939.
- Post Office - Milton MAThe distinctive branch post office in Milton, Massachusetts was constructed by the Treasury Department in 1936.
- Post Office - Milton PAThe historic post office building in Milton was completed in 1934 with federal Treasury Department funds. The exterior of the post office contains several remarkable pieces of New Deal artwork.
- Post Office - Minden NEConstructed in 1937, this Minden post office is also the site of William Bunn's 1939 mural, "1848, Fort Kearney, Protectorate on the Overland Trail, 1871," painted for the Treasury Section of Fine Arts.
- Post Office - Mineola NYThe historic post office building in Mineola, New York was constructed with federal Treasury Department funds in 1935-7. The building is still in service.
- Post Office - Minerva OHThe historic post office in Minerva, Ohio was constructed in 1937 with federal Treasury Department funds. The building is still in service.
- Post Office - Missouri Valley IAThe historic Missouri Valley Post Office was constructed with New Deal funds in 1937. The building, which houses an example of New Deal artwork, is still in service.
- Post Office - Mobridge SDThe historic post office in Mobridge, South Dakota was constructed with federal Treasury Department funds. The building, which houses an example of New Deal artwork inside, is still in use today.
- Post Office - Moline ILThe historic post office building in Moline, Illinois was constructed in 1934 with federal Treasury Department funds. The building, which houses an example of New Deal artwork, is still in service.
- Post Office - Monett MOBuilt by the US Treasury Department in 1937.
- Post Office - Monroeville ALThe historic post office in Monroeville, Alabama was constructed in 1937-8 with federal Treasury Department funds. The building, which houses an example of New Deal artwork, is still in service today.
- Post Office - Montesano WAThe historic post office in Montesano, Washington was constructed with federal Treasury Department funds. The building, which was constructed ca. 1935, is still in use today.
- Post Office - Montevallo ALThe historic post office in Montevallo, Alabama was constructed in 1937 with federal Treasury Department funds. The building, which houses an example of New Deal artwork inside, is listed on the National Register of Historic Places and is still in use today.
- Post Office - Montgomery WVThe historic post office in Montgomery, West Virginia was constructed with federal Treasury Department funds. The building, which was constructed in 1935, is still in service.
- Post Office - Monticello ILThe historic post office in Monticello, Illinois was constructed in 1934 with federal Treasury Department funds. The building is still in service.
- Post Office - Monticello INThe historic post office in Monticello, Indiana was constructed in 1939 with federal Treasury Department funds. The building, which houses an example of New Deal artwork, is still in service.
- Post Office - Monticello NYThe historic post office in Monticello, New York was constructed with federal Treasury Department funds. The building, which was completed in 1935, is still in use today.
- Post Office - Montpelier OHThe historic post office building in Montpelier, Ohio was constructed with Treasury Department funds about 1940. The building is still in use today and houses a Section of Fine Arts mural by Leonard Ahneman.
- Post Office - Moorestown NJThe historic post office in Moorestown, New Jersey was constructed with Treasury Department funds. The building, which was completed in 1935, is still in use today.
- Post Office - Moravia NYThe historic post office in Moravia, New York was constructed with federal Treasury Department funds. The building, which was constructed in 1940-1 and houses an example of New Deal artwork inside, is still in use today.
- Post Office - Morganfield KYThe historic post office in Morganfield, Kentucky was completed in 1937 with funds provided by the Treasury Department. The building, which houses an example of New Deal artwork, is still in service.
- Post Office - Morris MNThe historic post office in Morris, Minnesota was constructed in 1938 with federal Treasury Department funds. The building, which houses an example of New Deal artwork, is still in use today.
- Post Office - Morrison ILConstructed by the Treasury Department in 1934.
- Post Office - Mount Ayr IABuilt in 1939.
- Post Office - Mount Hope WVThe historic post office in Mount Hope, West Virginia was constructed with federal Treasury Department funds. The building, which was constructed in 1940, houses an example of New Deal artwork and is still in service.
- Post Office - Mount Joy PAThe post office in Mount Joy, Pennsylvania was constructed with federal Treasury Department funds in 1935. The building is still in use today.
- Post Office - Mount Pleasant IAThe post office in Mount Pleasant, IA was constructed in 1935.
- Post Office - Mount Vernon MOConstructed by the US Treasury Department in 1937.
- Post Office - Mt. Carroll ILThe historic post office in Mt. Carroll, Illinois was constructed in 1940 with federal Treasury Department funds. The building, which houses an example of New Deal artwork, is still in use today.
- Post Office - Mt. Gilead OHThe historic post office building in Mount Gilead, Ohio was constructed with federal Treasury Department funds ca. 1937. The building, which houses a New Deal mural inside, is still in use today.
- Post Office - Mt. Morris ILThis post office was constructed with New Deal funds circa 1936-1937.
- Post Office - Mt. Pleasant TNThe post office's "blend of modernist elements with an overall symmetrical shape reminiscent of the state's other Colonial Revival post offices" (Van West, 2001, p. 69) is "considered one of the best examples of this design still extant in Tennessee (Davis et al., 2003, p. 2). It was one of some 200 post offices constructed by the Federal Works Agency in smaller communities across the nation during 1940.
- Post Office - Mt. Sterling ILThe post office in Mt. Sterling was completed in 1940 with funds provided by the Treasury Department. It is also the site of Henry Bernstein's 1941 mural, "The Covered Bridge," completed with funds provided by the Treasury Section of Fine Arts and viewable in the lobby.