Waldorf, Maryland is an unincorporated community and census-designated place in Charles County, Maryland, United States. It is 23 miles (37 km) south-southeast of Washington, D.C. The population of the census-designated area only (now including St. Charles) was 67,752 at the 2010 census. Waldorf was settled before 1900 as a rural crossroads with a train station and was called "Beantown" after a local family. Waldorf is now largely subsumed by the large planned community of St. Charles.
Waldorf's original name was Beantown. In 1880 the General Assembly of Maryland by an act changed the name in "Waldorf" in honor of William Waldorf Astor (1848–1919), the great-grandson of John Jacob Astor (1763–1848), who was born in Walldorf, Palatinate, Germany. On July 29, 1908 the city "Plumb Valley" in Waseca County, Southern Minnesota changed its name into "Waldorf" after Waldorf/MD. Once a tobacco market village, it came to prominence in the 1950s as a gambling destination after slot machines were legalized in Charles County in 1949. The boom lasted until 1968 when gambling was once again outlawed. Its subsequent substantial growth as a residential community began with a 1970 loan package from the Department of Housing and Urban Development which fueled the giant planned community of St. Charles, south of Waldorf.
St. Catharine, or the Dr. Samuel A. Mudd House, was listed on the National Register of Historic Places in 1974.