Here are the last days you can register to vote for the 2020 primary elections in every state and how to do it - Business Insider

The deadlines for registering to vote vary by state. Each US state and territory has its own dates and rules for registering to vote in person, online, and by mail, for both the primaries and the general election. This chart lists all the dates for registering before the primary elections for 2020.....
https://www.businessinsider.com/how-to-register-to-vote-when-to-register-deadlines