In-Person: Saturday before Election Day at the county clerk's office. 28 days before Election Day otherwise
By Mail: Postmarked 28 days before Election Day. However, an application may be accepted through the Friday following the deadline if the application is postmarked before the deadline.
Online: 28 days before Election Day.
New Mexico
Registration
Requirements
To register in New Mexico you must:
be a citizen of the United States
be a resident of the State of New Mexico
be 18 years of age at the time of the next election
not have been denied the right to vote by a court of law by reason of mental incapacity and, if I have been convicted of a felony, I have completed all conditions of probation or parole, served the entirety of a sentence or have been granted a pardon by the Governor.
Nobody will ever deprive the American people of the right to vote except the American people themselves—and the only way they could do this is by not voting.
Franklin D. Roosevelt, 1882-1945 (Thirty-Second President of the United States)