Adelphi, Maryland

Coordinates: 38°59′49″N 76°58′0″W / 38.99694°N 76.96667°W / 38.99694; -76.96667
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Adelphi, Maryland
The Adelphi Mill in July 2007
The Adelphi Mill in July 2007
Location of Adelphi, Maryland
Location of Adelphi, Maryland
Coordinates: 38°59′49″N 76°58′0″W / 38.99694°N 76.96667°W / 38.99694; -76.96667
Country United States
State Maryland
County Prince George's
 • Total2.72 sq mi (7.04 km2)
 • Land2.72 sq mi (7.03 km2)
 • Water0.00 sq mi (0.01 km2)
171 ft (52 m)
 • Total16,823
 • Density6,194.04/sq mi (2,391.72/km2)
Time zoneUTC−5 (Eastern (EST))
 • Summer (DST)UTC−4 (EDT)
ZIP Codes
20783, 20787
Area codes301, 240
FIPS code24-00400
GNIS feature ID0596997

Adelphi is an unincorporated area and census-designated place in Prince George's County, Maryland, United States.[2] Per the 2020 Census, the population was 16,823.[3] Adelphi includes the following subdivisions; Adelphi, Adelphi Park, Adelphi Hills, Adelphi Terrace, Adelphi Village, Buck Lodge, Chatham, Cool Spring Terrace, Hillandale Forest, Holly Hill Manor, Knollwood, Lewisdale, and White Oak Manor.


The unincorporated Adelphi community takes its name from the historic Adelphi Mill, established in 1796 along the Northwest Branch of the Anacostia River. and continues to attract visitors and can be rented for special functions. During the 19th century, George Washington Riggs acquired much of the area northeast of Washington, D.C., as his Green Hill estate in the Chillum Manor district. That estate included present-day Adelphi. In the early 1920s, part of the area was acquired by Leander McCormick-Goodhart as part of his Langley Park estate.[4] Labor organizer Mary Harris "Mother" Jones died in 1930, at the farm of Walter and Lillie May Burgess near Powder Mill and Riggs Roads in present-day Adelphi. A marker was erected by the Maryland State Highway Administration commemorating Mother Jones at her death site. Unlike its nearby neighbors Hyattsville and College Park, the area remained relatively undeveloped until immediately following World War II. At that time, subdivisions quickly developed. To distinguish it from the other neighboring unincorporated communities of Lewisdale and Langley Park, the growing subdivisions banded together in the mid-1950s and adopted the name "Adelphi" to reflect their commitment to the preservation of the historic mill of the same name. A community focal point that originally developed in the late 1950s is the Adelphi Pool, a private pool in the Adelphi neighborhood, located next to George Washington Cemetery on Riggs Road. Use of the Adelphi Pool requires paid membership or being accompanied by a member and paying a small fee. The Adelphi pool offers swimming lessons and also features swim teams which compete against each other. Two notable features of the Adelphi Pool are its long water slide and basketball hoop.

In 1971, the Harry Diamond Laboratories was established on 137 acres (0.55 km2) in the northern part of Adelphi. That facility continues as the Adelphi Laboratory Center, Army Research Laboratory (ARL), the U.S. Army's corporate research laboratory.[5] Other adjacent federal facilities include the National Archives at College Park and headquarters of the Food and Drug Administration.

Historic sites[edit]

The following is a list of historic sites in Adelphi identified by the Maryland-National Capital Park and Planning Commission:[6]

Site name Image Location M-NCPPC Inventory Number Comment
1 Adelphi Mill and Storehouse
8401 and 8402 Riggs Road 65-006
2 Cool Spring Farm (Miller’s House) 2201 Cool Spring Road 65-005
3 Gallant House 3124 Powder Mill Road 61-013


Adelphi is located at 38°59′49″N 76°58′0″W / 38.99694°N 76.96667°W / 38.99694; -76.96667 (38.996860, −76.966755).[7]

According to the United States Census Bureau, the Census Designated Place (CDP) has a total area of 2.7 square miles (7.1 km2), all land.[8]

Adjacent areas[edit]


Historical population
U.S. Decennial Census[9]
2010[10] 2020[11]

2020 census[edit]

Adelphi CDP, Maryland – Racial and ethnic composition
Note: the US Census treats Hispanic/Latino as an ethnic category. This table excludes Latinos from the racial categories and assigns them to a separate category. Hispanics/Latinos may be of any race.
Race / Ethnicity (NH = Non-Hispanic) Pop 2010[10] Pop 2020[11] % 2010 % 2020
White alone (NH) 1,980 1,571 13.12% 9.34%
Black or African American alone (NH) 5,291 4,953 35.07% 29.44%
Native American or Alaska Native alone (NH) 37 36 0.25% 0.21%
Asian alone (NH) 1,168 1,367 7.74% 8.13%
Pacific Islander alone (NH) 5 6 0.03% 0.04%
Some Other Race alone (NH) 53 91 0.35% 0.54%
Mixed Race or Multi-Racial (NH) 207 336 1.37% 2.00%
Hispanic or Latino (any race) 6,345 8,463 42.06% 50.31%
Total 15,086 16,823 100.00% 100.00%

2000 Census[edit]

As of 2000, there were 14,998 people, 5,332 households, and 3,321 families that were reported to be living in Adelphi, Maryland. The population density was 5,067.9 inhabitants per square mile (1,956.7/km2). There were 5,627 housing units at an average density of 1,901.4 per square mile (734.1/km2). The racial makeup of the CDP was quite diverse, including 29.48% White, 39.83% African American, 0.28% Native American, 9.95% Asian, 0.06% Pacific Islander, 15.04% from other races, and 5.36% from two or more races. Hispanic or Latino of any race were 25.74% of the population.

There were 5,332 households, out of which 30.6% had children under the age of 18 living with them, 42.5% were married couples living together, 13.5% had a female householder with no husband present, and 37.7% were non-families. 27.5% of all households were made up of individuals, and 6.1% had someone living alone who was 65 years of age or older. The average household size was 2.77 and the average family size was 3.35.

In the CDP, the age distribution of the population included 22.7% under the age of 18, 13.0% from 18 to 24, 35.7% from 25 to 44, 19.1% from 45 to 64, and 9.5% who were 65 years of age or older. The median age was 32 years. For every 100 females, there were 98.1 males. For every 100 females age 18 and over, there were 96.6 males.

The median income for a household in the CDP was $45,827, and the median income for a family was $53,839. Males had a median income of $32,495 versus $31,932 for females. The per capita income for the CDP was $20,952. About 6.6% of families and 9.0% of the population were below the poverty line, including 6.2% of those under age 18 and 7.4% of those age 65 or over.

Government and infrastructure[edit]

The Prince George's County Police Department serves Adelphi through District 1,[12] with its station in Hyattsville.[13]

The Chillum-Adelphi Volunteer Fire Department (CAVFD) serves Adelphi. The station is in Langley Park CDP and has an Adelphi postal address.[14][15] In March 1951 and June 8, 1951 the CAVFD was established and chartered, respectively. From November and March 1953 the fire station on Riggs Road was constructed; the County Volunteer Firemen's Association designated it Station No. 34. Portions of Station No. 34 were rebuilt in the early 1960s, and it was rededicated on November 16, 1963. In 1962 the CAVFD began building a substation, No. 44, which was dedicated on November 16, 1963, but in 1992 it sold the substation to the county government.[16]

The University System of Maryland has an office in College Park,[17] which has an Adelphi postal address and is called the "Adelphi Office".[18] Formerly it was the headquarters of the entire system.[19]


Adelphi is the home of the University of Maryland Global Campus, and the community is located near the University of Maryland main campus in College Park.

Adelphi is served by the Prince George's County Public Schools system.[20] In 2000, a new elementary school opened in the community dedicated to labor organizer Mary Harris "Mother" Jones.[21]

Elementary schools in Adelphi:[22]

  • Adelphi Elementary School[23]
  • Cherokee Lane Elementary School[24]
  • Cool Spring Elementary School][25]
  • Mary Harris "Mother" Jones Elementary School[26]

A southeastern section is zoned to University Park Elementary School in University Park.[22]

Most residents are zoned to Buck Lodge Middle School in Adelphi and High Point High School in Beltsville. A southeastern section is zoned to Hyattsville Middle School and Northwestern High School in Hyattsville.[27][28]

Notable people[edit]

See also[edit]

  • Avenel-Hillandale, name of a census-designated place that was part of Adelphi in 1970.


  1. ^ "2020 U.S. Gazetteer Files". United States Census Bureau. Retrieved April 26, 2022.
  2. ^ U.S. Geological Survey Geographic Names Information System: Adelphi, Maryland
  3. ^ "Adelphi CDP, Maryland". United States Census Bureau. Retrieved March 13, 2022.
  4. ^ "Adelphi Mill Is Reopened to the Public," The Washington Post and Times-Herald, Dec 6, 1954, pg. 21.
  5. ^ "Adelphi Laboratory Center". Entry for Adelphi Laboratory Center [Harry Diamond Laboratories], US Army Research Laboratory (ARL). April 15, 2008.
  6. ^ M-NCPPC Illustrated Inventory of Historic Sites (Prince George's County, Maryland), 2006 Archived 2008-07-25 at the Wayback Machine.
  7. ^ "US Gazetteer files: 2010, 2000, and 1990". United States Census Bureau. February 12, 2011. Retrieved April 23, 2011.
  8. ^ "Geographic Identifiers: 2010 Demographic Profile Data (G001): Adelphi CDP, Maryland". United States Census Bureau. Retrieved December 14, 2011.
  9. ^ "Decennial Census of Population and Housing by Decades". US Census Bureau.
  10. ^ a b "P2 Hispanic or Latino, and Not Hispanic or Latino by Race – 2010: DEC Redistricting Data (PL 94-171) - Adelphi CDP, Maryland". United States Census Bureau.
  11. ^ a b "P2 Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) - Adelphi CDP, Maryland". United States Census Bureau.
  12. ^ Rucker, Philip; Eric Rich; Allison Klein (July 1, 2006). "Three Dead After Gang-Related Shooting". The Washington Post. Retrieved September 19, 2018. In District 1, the police district that includes Adelphi, Langley Park and other communities,[...]
  13. ^ "District 1 Station - Hyattsville. Prince George's County Police Department. Retrieved on September 9, 2018. Beat map.
  14. ^ "2010 CENSUS - CENSUS BLOCK MAP: Langley Park CDP, MD." U.S. Census Bureau. Retrieved on January 31, 2018.
  15. ^ "Where We Are." Chillum-Adelphi Volunteer Fire Department. Retrieved on September 9, 2018. "The Chillum-Adelphi Volunteer Fire Department Prince George’s County, MD – Co. 34 7833 Riggs Rd, Adelphi, MD 20783"
  16. ^ "Department History." Chillum-Adelphi Volunteer Fire Department. Retrieved on September 9, 2018.
  17. ^ "College Park Route Number Map" (PDF). Maryland Department of Transportation. Retrieved February 7, 2024. U of MD Central Admin.
  18. ^ "USM Office". University System of Maryland. Retrieved February 5, 2024. USM Headquarters 701 E. Pratt St. Baltimore, MD 21202 Adelphi Office/Mailing Address for All USM Offices 3300 Metzerott Road Adelphi, MD 20783-1690 - Annapolis and Columbia are stated as office locations. The "Adelphi" office is actually in College Park, as indicated here.
  19. ^ "USM Office". University System of Maryland. Archived from the original on June 18, 2006. Retrieved February 5, 2024.
    "Contact/Visit Us" (Archive). University System of Maryland. Retrieved on September 18, 2012. "3300 Metzerott Road Adelphi, MD 20783" – See also Directions to USM Office (Archive)
  20. ^ "2010 CENSUS - CENSUS BLOCK MAP: Adelphi CDP, MD." U.S. Census Bureau. Retrieved on January 31, 2018.
  21. ^ "Who is "Mother Jones"?". Mary Harris Mother Jones Elementary School. Retrieved June 16, 2019.
  22. ^ a b "NEIGHBORHOOD ELEMENTARY SCHOOLS AND BOUNDARIES SCHOOL YEAR 2017-2018." Prince George's County Public Schools. Retrieved on January 31, 2018.
  23. ^
  24. ^
  25. ^
  26. ^ Archived 2013-07-19 at the Wayback Machine
  27. ^ "NEIGHBORHOOD MIDDLE SCHOOLS AND BOUNDARIES SCHOOL YEAR 2017-2018." Prince George's County Public Schools. Retrieved on January 31, 2018.
  28. ^ "NEIGHBORHOOD HIGH SCHOOLS AND BOUNDARIES SCHOOL YEAR 2017-2018." Prince George's County Public Schools. Retrieved on January 31, 2018.

External links[edit]