See 8 CFR 316.2(a)(3) and (4)
(a) General. Except as otherwise provided in this chapter, to be eligible for naturalization, an alien must establish that he or she:
(3) Has resided continuously within the United States, as defined under §316.5, for a period of at least five years after having been lawfully admitted for permanent residence;
(4) Has been physically present in the United States for at least 30 months of the five years preceding the date of filing the application;
also INA 316 (a)(1) and (2) , 8 USC 1427
(a) Residence - No person, except as otherwise provided in this subchapter, shall be naturalized unless such applicant,
(1) immediately preceding the date of filing his application for naturalization has resided continuously, after being lawfully admitted for permanent residence, within the United States for at least five years and during the five years immediately preceding the date of filing his application has been physically present therein for periods totaling at least half of that time, and who has resided within the State or within the district of the Service in the United States in which the applicant filed the application for at least three months,
(2) has resided continuously within the United States from the date of the application up to the time of admission to citizenship