Residents of Washington DC have long been frustrated by a lack of (voting) representation in the US Congress, as well as local governance problems arising from the city's status as a federal district.
Members of Congress have in the past introduced legislation intending to convert much of the current federal district into a new state. President-elect Biden has in the past vocalized support for such resolutions.
There are numerous proposals for the exact details of such a transition, most including a prominent 'rump federal district' around the US Capitol building.