is an urbanized, unincorporated area in Montgomery County, Maryland, United States. After Baltimore and Columbia, the Silver Spring CDP is the third most populous place in Maryland.
The urbanized, oldest, and southernmost part of Silver Spring is a major business hub that lies at the north apex of Washington, D.C. As of 2004, the Central Business District (CBD) held of office space, 5216 dwelling units and of parkland. The population density of this CBD area of Silver Spring was 15,600 per square mile all within and approximately 2½ square miles in the CBD/downtown area.
The community has recently undergone a significant renaissance, with the addition of major retail, residential, and office developments.
Silver Spring takes its name from a mica-flecked spring discovered there in 1840 by Francis Preston Blair, who subsequently bought much of the surrounding land. Acorn Park, tucked away in an area of south Silver Spring away from the main downtown area, is believed to be the site of the original spring.
As an unincorporated area, Silver Spring's boundaries are not officially defined. Residents of a huge swath of Montgomery County have Silver Spring mailing addresses. This area extends roughly from the Washington, D.C., Prince George's County, Maryland and Howard County, Maryland lines to the south, east and north, and Rock Creek Park and Plyers Mill Road to the west and north-west. These boundaries make Silver Spring larger in area than any city in Maryland except for Baltimore. Among some notable landmarks is the world headquarters of Discovery Communications, the AFI Silver, and the headquarters of the Seventh-day Adventist Church.
whose center is located at 39°1' North latitude, 77°1' West longitude. The United States Geological Survey locates the center of Silver Spring at , notably some distance from the Census Bureau's datum. By another definition, Silver Spring is located at (39.004242, -77.019004). The definitions used by the Silver Spring Urban Planning District, the United States Postal Service, the Greater Silver Spring Chamber of Commerce, etc., are all different, each defining it for its own purposes.
According to the United States Census Bureau, the community has a total area of 9.4 square miles (24.4 km²). Twenty-four point four km² (24.4 km²) (9.4 sq mi) of it is land and none of the area is covered with water (although there are numerous creeks and small lakes).