And here's the most comprehensive chart of voter registration deadlines (not easy to fit all that info onto one sheet, so you have to zoom in):

Imminent voter registration deadlines: Sun. 10/6: Alaska and Rhode Island Mon. 10/7: Arizona, Arkansas, Florida, Georgia, Indiana, Kentucky, Mississippi, Montana, Ohio, Tennessee, Texas Check your registration status. Register/re-register if needed. Vote.gov

Register to vote in your state | Vote.gov

Find the information you need to make registration and voting easy. Official voter registration website of the United States government.