I became a green card holder through my wife, who was born in the U.S. and so was a U.S. citizen. I've had my green card for a little over three years. Tragically, however, my wife died last year. I would like to apply to become a U.S. citizen as soon as possible, so as to help my parents immigrate to the United States. Can I use the exception allowing spouses of U.S. citizens to apply after three years with a green card?
Sadly, the portion of U.S. immigration law allowing a person who has been a permanent (or conditional) resident and married to, as well as living with, a U.S. citizen for three years to apply for U.S. citizenship at the end of that time no longer applies if the U.S. citizen dies. (See the Immigration and Nationality Act at I.N.A. Section 319(a) or 8 U.S.C. Section 1430(a).)
Although the I.N.A. doesn't say this, it is referenced in the Code of Federal Regulations (8 CFR 319.1(b)(2)(i).), which states:
A person is ineligible for naturalization as the spouse of a United States citizen under Section 319(a) of the Act if, before or after the filing of the application, the marital union ceases to exist due to death or divorce, or the citizen spouse has expatriated.
Therefore, you will have to wait the full period required of most applicants before filing your N-400 application for naturalization, normally five years minus 90 days (unless another exception applies to you). (See When Can I Apply for U.S. Citizenship? for a full discussion of minimum time required before applying.)
In fact, even if you had already submitted your N-400 before your wife died, you would not be allowed to go forward with your swearing-in ceremony if you were relying on her citizenship to apply early. This is implied by the C.F.R., which says "before or after the filing of the application."
And it's made even clearer in a policy manual published by U.S. Citizenship and Immigration Services (USCIS), which states, "An applicant is ineligible to naturalize as the spouse of a U.S. citizen if the U.S. citizen dies any time prior to the applicant taking the Oath of Allegiance."