Dear Madame L,
I live in a state which has early voting, and so I voted last week. But the more I read about the two candidates, the less sure I am that I voted right. Is it possible to change my vote?
Still Undecided, Even Though I Voted
Madame L didn't know the answer to your question, and didn't know much at all about early voting, until she looked it up online.
Check out Wikipedia's excellent treatment of early voting not only in the U.S. but around the world. Here's a map showing where early voting is allowed.
No-excuse early voting in U.S. states, as of September 2007.
Key: Blue: in-person and postal
Magenta: in person only
Green: postal only
The early voting has already started in Iowa (Sept. 27). According to another news article Madame L read, 35 states allow early voting, and about 40 million people voted early in the 2008 election (one-third of the total votes!).
Unfortunately --- or not --- it's not possible to "vote early and often": At least, legally, once you've cast your ballot, you cannot change it.