My flight arrives in Atlanta from Venice now at 6:00pm and we have a 7:22pm flight to DC.
Do I have to collect my checked luggage and then proceed through immigration or does it get checked through to DC?
Is it one ticket?
Yes. We bought it at the same time
Atlanta is a great airport for transferring to another flight.
Yes, you will have to go through immigration and customs after getting your luggage, then turn them in for your next flight.
Still, you should be able to make the flight. There is an underground subway inside airport security that is called the planetrain. It will get you to your next terminal quickly.
On my last international trip, the airport had someone collecting bags just past immigration or customs so it took no time at all to get to the connecting flight.
That is possible but very tight. Slight correction to one of the replies above (baggage is collected after immigration but before customs). Steps are (1) get off plane (which can take a while especially if you're toward the back); (2) immigration; (3) collect checked bag (it will probably be waiting for you on the belt, but that's because it will have taken you some time to get through the immigration line); (4) customs (but this isn't really a stop, you just walk through unless they stop you for some reason); (5) recheck checked bag (this is very quick, it's already tagged so you just give it to the agent manning a conveyer belt); (6) security; (7) proceed to gate for your next flight. Steps (2) and (6) are especially where there can be delays, and also don't underestimate (7) -- the train between terminals is fairly quick, but the walk to the gate can be long. I did this through Atlanta in December with about a 2 hour connection and just barely made it (and my bag did not, but was on the next DC flight an hour later); that one had a delay in deplaning and a fairly long immigration line. But there are a number of later flights ATL-DC (you don't specify which DC airport, presumably DCA (Reagan), but there's also IAD (Dulles) the airline (I assume it's Delta) can put you on if you miss it, assuming it's a single ticket.
I love and appreciate my hometown airport. It has so many scaffolds, such as the plane train, moving sidewalks, etc. to help you get from terminal to terminal. With that being said, is there anyway you can carry on your luggage? That is a very tight connection to make.
