The lights are on
To get out of the map is simple, first you need to make sure you have found the area Takoma Industrial, one of the five Behemoth locations. Next you need to enter the Factory in the area, the huge building in the area. Once inside walk up the first flight of stairs you see which should be to your left. Exit through the door and walk down a pathway until you find a tent. Now, turn around and walk on the side of the walkway (between the railing and the water, on the stone) it's not that hard to do. Once you pass the huge scrap metal pile, jump into the water. You should see some pipes on the other side of the river with walkways on top of them. Jump on those and walk forward until you see an alleyway, turn left and follow that. Now follow that pathway until you see a large radiation pool filled with ghouls. Get rid of the ghouls and walk towards the tent. In the tent is two bodies, a computer documenting the two scientists experiments, and a few supplies. Raid it if you want, now turn left from the tent and start climbing up the pile of rock and jump through the space in between the two buildings in front of you, jump down the piles that are in front of you and congratulations, you're outside of the map! (Also, if you go further to your right, you'll eventually find a huge destroyed Pentagon outside of the map, have fun!)
I suggest saving before going outside the map, although you can find quite a few ways back inside the map.
allot further to the right is another washington monument.
completely useless but still cool