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.
Politics are a part of religion in such a country as this, and Christians must do their duty to the country as a part of their duty to God … Christians seem to act as if they thought God did not see what they do in politics. But I tell you, He does see it, and He will bless or curse this nation, according to the course they take.
Charles Finney, 1792-1875 (Nineteenth Century Evangelist and Author)