To be eligible to become a U.S. Citizen through naturalization you must:
- Be a legal permanent resident that has been living in the U.S. Continuously for five years
- If you received your green card through marriage, then you can apply for citizenship after you've been a legal permanent resident for three years
- Haven't left the US for trips of 6 months or longer in the last 5 years (unless you were out of the country as part of service in the military)
- You must have lived in the USCIS district or state where you are applying for at least 3 months before applying
To learn more about residency requirements involved in applying for citizenship, you should speak with a lawyer.