You need to have held your green card for at least 5 years before you can apply for U.S. citizenship.

If you’re married to a U.S. citizen, you can apply for citizenship after 3 years of holding a green card.

Typically 5 years, However, if you are in active U.S. military service, you may be eligible to apply for citizenship sooner

You must maintain continuous residence in the U.S. for 5 years, with no prolonged trips abroad that may interrupt your residence.