Canadians Applying for U.S. Citizenship Based on Marriage
Canadian citizens who are U.S. permanent residents through marriage may be eligible to naturalize as a U.S. citizen.
If you obtained permanent residency through marriage to a U.S. citizen, they can apply to naturalize three years after first becoming a permanent resident. During these three years, the applicant must have been physically present in the United States for at least half of this time (18 months/1.5 years). Further, applicant cannot have resided outside of the U.S. continuously for more than one year. If so, that breaks the continuous residency requirement and they will need to restart the three-year clock after re-entering.
Please click on U.S. Citizenship for more details.