Voting in more than one state (for the purposes of the statute, DC is considered a state) in the same federal election is a federal crime.
That law has been broken by at least thousands in the last few presidential elections, but, as with other types of election fraud and cheating, the perps are seldom if ever arrested and prosecuted.
Not to scoff at it or minimize it, this voting in more than one state is not the most "effective" type of election fraud and cheating in presidential elections. Far more pernicious and rarely talked about is electronic hacking into optical scanning and touch screen vote counting systems. That, targeted to several vital swing states, occurred to such an unprecedented extent in 2012, that it could very well have stolen the presidency for Obama vs. Romney!!!
Vote counting fraud and cheating, especially by high tech means, should be on the front burner in any discussion of election fraud and tamping down on it. It would be preferable to go back to paper ballots counted by hand and eye in open public, rather than rely on hackable computer systems to count votes.
Or purple fingers.
Thank you for sharing your insights, dear justiceseeker93!