[5] John Delaney, who represented the district after unseating 11-term incumbent republican Roscoe Bartlett, gave up the seat in 2018 to focus on his bid for president and was succeeded by fellow Democrat David Trone, who won re-election in 2020 as well.

The new sixth district was in the north-east corner of the state east of Baltimore, covering essentially the modern counties of Harford, Cecil and Kent.

In his bid for an 11th term, Bartlett was defeated by Democrat John Delaney, who lives in the Montgomery County portion of the district, by over 21 points.

[10] In 2013, Republican voters filed a federal lawsuit, alleging that the Democratic legislature and Governor Martin O'Malley had engaged in partisan gerrymandering, redrawing the 6th district after the 2010 census in a way that intentionally and unconstitutionally diluted Republican voters by including parts of the heavily Democratic Washington suburbs.

A federal district judge initially dismissed the lawsuit, as did the Fourth Circuit Court of Appeals, for failure to state a claim.

The case went back to the lower courts where a three judge panel ruled that the Republicans could not prove that John Delaney's election in 2012 was a result of the redistricting.

Republican voters again appealed to the Supreme Court, which agreed to hear the case, Benisek v. Lamone, in December 2017.