It’s on the Obama website.
Took me less than a minute.
Enter name and address, and it will check you against the official voter role to confirm that you’re registered to vote. Cool! (And yes, they’re harvesting email addresses, but you can enter null@null.com and the system accepts it.)
The system will also tell you whether and when (but not where) early voting is available in your state.
This is worth doing, and telling your friends about. Not only does it ensure your vote, it keeps you from holding up the line for everyone else on Election Day. And if you’re in an early voting state (most are), please do vote early if you can. Every vote cast before Election Day makes it that much easier for the people who do vote on Election Day.
Update: A reader reports that the software isn’t foolproof. First, the site told her that she wasn’t registered, though she voted just last month. Then, “I finally got it to work, and I was listed as registered. The site seems to have some bugs, and was interacting in funny ways with Auto Fill. Took me four tries to get it to work.”