Why do we in the United States have voting districts? Wouldn't it be better to allow people to vote wherever is most convenient and then group relevant votes based on the voters' addresses?

Since we have electronic polls, I don't think it would be too difficult to implement. If security is an issue, couldn't we just use extra long variable-length encryption keys that change every few seconds, along with server and host authentication?

Wouldn't more people vote if they could just go to the most convenient poll?