All speculation on part, naturally, but I think it'd be hard for the show to depict Alexandria/D.C. while keeping production in Georgia and not having to do some extensive, and expensive, location shooting.
Well the film Dumb and Dumber II
was filmed here in GA and they turned the city of Marietta into El Paso Texas.
Regarding this episode - it was a little slow for me. The story arcs are starting to get for me a little redundant and so are their encounters with the zombies.