Election guide: Here's a full list of 2016 voter registration deadlines by state

AP

With nearly 70% of citizens registered to vote, there are still millions of eligible voters who are still not able to cast a ballot on election day. Citizens who will be 18 or older at the time of the election can register to vote in most states. Other states offer pre-registration options to people as young as 16. A majority of states offer online voter registration beyond typical in-person or mail-in registration. 

But the key to registering to vote: knowing your deadline. A majority of states do not have same-day voter registration and require voters to register weeks before the election. And states have updated details on how long voters have to register. Google cannot be trusted for voter registration deadlines.

Here's a list of voter registration deadlines for every state:

Alabama — Monday, Oct. 24

Alaska — Sunday, Oct. 9

Arizona — Monday, Oct. 10

Arkansas — Sunday, Oct. 9

California — Monday, Oct. 24

Colorado — state offers election day registration in-person

Connecticut — state offers election day registration in-person

Delaware — Saturday, Oct. 15

District of Columbia — state offers election day registration in-person

Florida — Tuesday, Oct. 11

Georgia — Tuesday, Oct. 11

Hawaii — Monday, Oct. 10

Idaho — state offers election day registration in-person at the polls

Illinois — state offers election day registration in-person at specific facilities 

Indiana — Tuesday, Oct. 11

Indiana voters at the polls during the state's 2016 presidential primary.  Scott Olson/Getty Images

Iowa — state offers election day registration 

Kansas — Tuesday, Oct. 18

Kentucky — Tuesday, Oct. 11

Louisiana — Sunday, Oct. 9

Maine — state offers election day registration in-person

Maryland — Tuesday, Oct. 18

Massachusetts — Wednesday, Oct. 19

Michigan — Tuesday, Oct. 11

Minnesota — state offers election day registration in-person at the polls

Mississippi — Sunday, Oct. 9

Missouri — Wednesday, Oct. 12

Montana — state offers election day registration in-person

Nebraska — by mail, postmarked by Friday, Oct. 21; in-person, Friday, Oct. 28

Nevada — Tuesday, Oct. 18

New Hampshire — state offers election day registration in-person

A New Hampshire voter casts their ballot in the 2016 presidential primary.  David Goldman/AP

New Jersey — Tuesday, Oct. 18 

New Mexico — Tuesday, Oct. 11

New York — Friday, Oct. 14

North Carolina — Friday, Oct. 14

North Dakota — does not require voter registration

Ohio — Tuesday, Oct. 11

Oklahoma — Friday, Oct. 14 

Oregon — Tuesday, Oct. 18 

Pennsylvania — Tuesday, Oct. 11

Rhode Island — Sunday, Oct. 9 

South Carolina — Sunday, Oct. 9

Voters head to the polls during the South Carolina Democratic presidential primary in 2016.  Sean Rayford/Getty Images

South Dakota — Monday, Oct. 24

Tennessee — Tuesday, Oct. 11 

Texas — Tuesday, Oct. 11

Utah — by mail, Sunday, Oct. 9; online, Tuesday, Nov. 1

Vermont — Wednesday, Nov. 2

Virginia — Monday, Oct. 17

Washington — Monday, Oct. 10

West Virginia — Tuesday, Oct. 18

Wisconsin — state offers election day registration in-person at the polls

Wyoming — state offers election day registration in-person at the polls