Location of Eldersburg, Maryland
|• Total||42.2 sq mi (109.4 km2)|
|• Land||39.7 sq mi (102.8 km2)|
|• Water||2.5 sq mi (6.6 km2)|
|Elevation||643 ft (196 m)|
|• Density||769/sq mi (297.0/km2)|
|Time zone||Eastern (EST) (UTC-5)|
|• Summer (DST)||EDT (UTC-4)|
|GNIS feature ID||0590147|
Eldersburg is named after John Elder. The community was served by a post office in April 1850 in the Howard district of Anne Arundel County with the name "Eldersburgh". In 1851, Howard County was formed, and on October 28, 1871, the post office moved to Carroll County, retaining the "Eldersburgh" spelling. In December 1894, "Eldersburgh" was shortened to "Eldersburg". The Moses Brown House was listed on the National Register of Historic Places in 1980. Wesley Chapel Methodist Episcopal Church was listed in 1984.
Eldersburg is located in the southeastern portion of Carroll County at  It is bordered to the east by Baltimore County and to the south by Howard County, except where it is bordered by the town of Sykesville.(39.400802, -76.951475).
The center of Eldersburg is at the intersection of Maryland Route 26 (Liberty Road) and Maryland Route 32 (Sykesville Road). MD 26 leads east 20 miles (32 km) to downtown Baltimore and west 28 miles (45 km) to Frederick, while MD 32 leads north 15 miles (24 km) to Westminster, the Carroll County seat, and south 20 miles (32 km) to Columbia.
According to the United States Census Bureau, the Eldersburg CDP has a total area of 42.2 square miles (109.4 km2), of which 39.7 square miles (102.8 km2) is land and 2.5 square miles (6.6 km2), or 6.00%, is water.
As of the census of 2010, there were 30,531 people and 10,844 households within the CDP. The population density was 725.2 people per square mile (280.0/km²). The racial makeup of the CDP was 92.44% White, 3.42% African American, 0.22% Native American, 1.98% Asian, 0.44% from other races, 0.76% from two or more races, and 1.47% of the population were Hispanic or Latino of any race.
According to the 2000 Census, there were 9,138 households, of which 44.1% included children under the age of 18, 72.2% were married couples, 7.1% were single females, and 17.9% were non-families. 14.8% of all households were individuals, and 7.2% of households consisted of someone 65 years of age or older living alone. The average household size was 2.92, and the average family size was 3.25.
Census data found that 29.1% of the population were under the age of 18, 5.9% were 18 to 24, 31.9% were 25 to 44, 23.7% were 45 to 64, and 9.4% were 65 or older. The median age was 36. For every 100 females there were 101.3 males. For every 100 females age 18 and over, there were 98.4 males.
The median income for a household was $70,851, and the median income for a family was $75,848. Males had a median income of $51,473; females had a median income of $34,728. The per capita income was $25,639. About 1.6% of families and 2.4% of the population were below the poverty line, including 1.9% of those under age 18 and 4.6% of those age 65 or over.
Eldersburg is served by the Carroll County public school system. Elementary schools include Eldersburg Elementary, Carrolltowne Elementary, Piney Ridge Elementary, Freedom Elementary School, and Linton Springs Elementary. The middle schools are Sykesville Middle School and Oklahoma Road Middle School, and three high schools, Liberty High School, South Carroll High School and Century High School, span across Sykesville and Eldersburg.
- "Geographic Identifiers: 2010 Demographic Profile Data (G001): Eldersburg CDP, Maryland". U.S. Census Bureau, American Factfinder. Retrieved August 22, 2014.
- "Checklist of Maryland Post Offices" (PDF). Smithsonian National Postal Museum. 12 July 2007. Retrieved 17 May 2014.
- Kenny, Hamill, The Place Names Of Maryland: Their Origin and Meaning ISBN 978-0-938420-28-6
- National Park Service (2008-04-15). "National Register Information System". National Register of Historic Places. National Park Service.
- "US Gazetteer files: 2010, 2000, and 1990". United States Census Bureau. 2011-02-12. Retrieved 2011-04-23.
- "American FactFinder". United States Census Bureau. Retrieved 2008-01-31.