Maryland's 8th congressional district is concentrated entirely in Montgomery County. Adjacent to Washington, D.C., the 8th district takes in many of the city’s wealthiest inner-ring suburbs, including Bethesda, Chevy Chase, and Potomac. It also includes several more economically and racially diverse communities, the most populous of which are Rockville and Silver Spring.

With a median household income of $120,948, it is the ninth-wealthiest congressional district in the nation. The 8th district also has the eighth-highest share of residents with at least a bachelor's degree, at 63.9%. Those above-average numbers are largely due to the substantial presence of the federal government in nearby Washington, where thousands of the 8th district’s residents commute to work on a daily basis. Several federal agencies are likewise located within the 8th district, including the Food and Drug Administration, the National Institutes of Health, the Nuclear Regulatory Commission, and the Walter Reed National Military Medical Center. Two Fortune 500 companies are headquartered in the district: Lockheed Martin and Marriott International.^[3] Almost 40% of the district's residents are immigrants, with the largest numbers coming from El Salvador, Ethiopia, India, China, Korea, Guatemala, and Peru. The district includes the Little Ethiopia area of Silver Spring and Takoma Park, and has the largest Ethiopian American population of any congressional district.^[4]

Politically, the district is heavily liberal. It has consistently sent Democratic representatives to Congress by wide margins since 2002. In 2020, Joe Biden won nearly 80% of its vote. Democrat Jamie Raskin has represented the seat since 2017.

The district was created after the 1790 census in time for the 1792 election, was abolished after the 1830 census, and was reinstated after the 1960 census.

During redistricting after the 2000 census, the Democratic-dominated Maryland legislature sought to unseat then-incumbent Republican Connie Morella^{[citation needed]}. One proposal went so far as to divide the district in two, effectively giving one to state Senator Christopher Van Hollen, Jr. and forcing Morella to run against popular Maryland State Delegate and Kennedy political family member Mark Kennedy Shriver^{[citation needed]}. The final redistricting plan was less ambitious, restoring an eastern, heavily Democratic spur of Montgomery County removed in the 1990 redistricting to the 8th District^{[citation needed]} (encompassing nearly all of the area "inside the Beltway"), as well as adding an adjacent portion from heavily Democratic Prince George's County. Although it forced Van Hollen and Shriver to run against each other in an expensive primary, the shift still made the district even more Democratic than its predecessor, and Van Hollen defeated Morella in 2002.

From 2003 to 2013 the district, in addition to the larger part of Montgomery County and the small portion of Prince George's County, included most of Frederick County (but not the City of Frederick), and southern Carroll County. The redrawn district was slightly less Democratic than its predecessor. While the Carroll and Frederick portions of the district tilted strongly Republican, the Montgomery County portion had twice as many people as the rest of the district combined, and Montgomery's Democratic tilt was enough to keep the district in the Democratic column. Since Morella left office, no Republican has crossed the 40 percent mark in the 8th District.

Since 2023, the following communities are located within the 8th district.^[5]

• Maryland's congressional districts
• List of United States congressional districts

• FairVote.org: Maryland's Redistricting News March 16, 2001 – October 18, 2001
• District boundaries, 1992–2002