Federal Role in Voter Registration: The National Voter Registration Act of 1993 and Subsequent Developments [Updated April 20, 2022] [open pdf - 1MB]
From the Document: "Historically, most aspects of election administration have been left to state and local governments, resulting in a variety of practices across jurisdictions with respect to voter registration. States can vary on a number of elements of the voter registration process, including whether or not to require voter registration; where or when voter registration occurs; and how voters may be removed from registration lists. The right of citizens to vote, however, is presented in the U.S. Constitution in the Fifteenth, Nineteenth, and Twenty-sixth Amendments. Beginning with the Voting Rights Act (VRA) in 1965, Congress has sometimes passed legislation requiring certain uniform practices for federal elections, intended to prevent any state policies that may result in the disenfranchisement of eligible voters. The National Voter Registration Act (NVRA) was enacted in 1993 and set forth a number of voter registration requirements for states to follow regarding voter registration processes for federal elections."
CRS Report for Congress, R45030
Congressional Research Service: https://crsreports.congress.gov/