* Washington, D.C.: Most of the interior scenes, including the iconic Georgetown house where Regan's family lived, were filmed in a studio in Washington, D.C.
* Maryland: Some exterior scenes were filmed in Georgetown, Maryland, including the house where the priest's apartment was located.
* New York City: The scenes at the hospital were filmed in New York City.
* Other locations: The film also used locations in Baltimore, Maryland, and Virginia.
It's important to note that while the film is set in Washington, D.C., much of the filming actually took place in nearby Maryland and Virginia due to tax incentives and studio availability.