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. One proposal went so far as to divide the district in two, effectively giving one to state SenatorChristopher Van Hollen, Jr. and forcing then-incumbent Connie Morella to run against popular Maryland State Delegate and Kennedy political family member Mark Kennedy Shriver. 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, as well as adding an adjacent portion from heavily Democratic Prince George's County located in . 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 mostly consisted of the larger part of Montgomery County, also including a small portion of Prince George's County. The district now includes most of Frederick County, southern Carroll County, and a swath of Montgomery County that narrows in the north and then widens in the south to encompass nearly all of the area "inside the beltway." The redrawn district is slightly less Democratic than its predecessor. While the Carroll and Frederick portions of the districts tilt strongly Republican, the Montgomery County portion has twice as many people as the rest of the district combined, and Montgomery's Democratic tilt is enough to keep the district in the Democratic column. When Van Hollen left his seat in a successful bid to succeed Barbara Mikulski in the U.S. Senate, Jamie Raskin won the Democratic primary to take over the seat. The primary campaign was the most expensive House race in 2016, due primarily to the large amounts spent by wealthy businessman and runner-up David Trone.
