They may only be 200 miles away, but keep in mind that that distance is measured vertically. Astronauts at the International Space Station vote for their choice of president with a birds eye view of the entire spectacle.
They are able to send and receive an absentee ballot to and from Mission Control in Houston.
By the way, the first American to vote in a presidential election from the vacuum of space was Leroy Chiao, in 2004.
Sources:
http://www.space.com/18341-astronaut-vote-election-space-station.html
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