Layer Descriptions


Early voting

Some states (including PA) do not permit early voting. Here, we code states that have created or eliminated early voting since 2006, or made the period longer or shorter.


Online Voter Registration

Many states have now implemented paperless voter registration systems, where those who have state-issued driver's licenses or state-issued identification cards--or in some cases, other applicants as well--can register to vote via the internet. Election officials then validate the information. In some states, legislation was passed to authorize online voter registration; in other states, it was not deemed necessary.


Rules governing groups registering voters

States that have instituted changes since 2006 making it harder or easier for groups wishing to conduct voter registration drives.


College Student Voting

States may no longer use lengthy durational residency requirements to exclude college students from voting in the jurisdiction where they attend college, and court decisions have established that students may register to vote in the jurisdiction where they attend college. However, it is unclear whether states may legally ask that students to demonstrate residency with an in-state driver's license, eligibility for jury duty, or (if they earn sufficient income) evidence of having paid taxes in the state. Some recent voter ID laws have made it more difficult for students to vote in the state where they attend school by rejecting student IDs as a valid form of identification.


States that pre-register soon-to-be voters in high school

States that have begun or expanded, or alternately ended or contracted since 2006, efforts to pre-register high school students at age 16, 17 (or those students who will be 18 before the next election). North Carolina's recent attempt to change voter registration rules, including an end to pre-registration of high school students, has been blocked in court.


Voter ID Laws

States that have tightened (or loosened) requirements for the kinds of identification documents voters need to present when appearing to vote in person


Absentee Voter ID

States that have added or removed requirements for submission of identification documents along with submission of absentee ballots


Absentee Voting

Absentee voting made harder or easier (including more/fewer restrictions on who can do so). Some states have no-excuse-needed absentee balloting; others (e.g., PA) require that a voter be away from his/her voting residence.


Mail-in Voting

Oregon, Washington, and Colorado now mail ballots to all voters. A number of other states allow some elections to take place by mail. That means the election takes place over a certain period, and not just a single day. Mail-in voting increases convenience for voters; evidence on whether it increases turnout (beyond the novelty period) is not clear. Mail-in voting would seem to address some of the reasons citizens use early voting or absentee voting, but it also eliminates the tradition of going to a local polling place and engaging in one sort of ritual of democracy. Florida now terms "formerly absentee voting" their vote-by-mail system, so the distinction between offering anyone an absentee ballot without excuse and having a mail-in ballot system is blurred. In a number of states, then, mail-in balloting and traditional election day voting at polling places both take place. Please see individual state write-ups for details. States that offer mail-in ballots only for precincts or small towns having a low number of registered voters are not counted in our map as having a mail-in-voting system in place.


Swing States

States in which the outcome of the presidential election was closely contested in an election, often termed battleground states.


Same Day Registration

No state can close voter registration earlier than thirty days before Election Day (the Supreme Court held lengthy residency requirements unconstitutional in 1972). However, some states make it possible to both register to vote and then vote on the day of election. Proof of residency and some form of identification (which varies by state) must be presented. If a state has early voting, it might also permit same day registration and voting during the early voting period. North Dakota is the only state that requires no voter registration, and on the map, we have included it with the states requiring no registration prior to election day.


States that Disenfranchise Felons

In Maine and Vermont, convicted felons retain their right to vote while incarcerated, but other states place restrictions on voting rights of those convicted of a felony. Some states disenfranchise felons only during their time in prison; some include the parole period; and a number of others include the period of probation. In some states, there may be a number of years of disenfranchisement post-parole or probation stipulated, and the restoration of voting rights may not be automatic. As of 2016, Iowa, Kentucky, and Florida impose lifetime felony disenfranchisement.


States that have consistently supported one party or the other Since the election of 1992

A number of states have voted consistently Republican or Democratic in presidential elections since 1992 (electoral college vote) shown in Red and blue on this map. States that have voted consistently for one party 5 out of 6 of these elections are shown with a color and pattern.


States covered in whole or in part by ยง5 of the Voting Rights Act in 2013

States, covered in whole (solid) or in part (pattern), that had to submit voting rule changes to the Justice Department under Section 5 of the Voting Rights Act because of a past history of practices restricting minority voting rights at the time Shelby County v. Holder (2013) effectively ended Section 5 preclearance.