Spouse of a Deceased U.S. Citizen
A widow/widower of a U.S. citizen may file an immigrant visa petition, form I-360 (PDF - 230 kb), on his/her own behalf in the immediate relative category if he/she had been married to the deceased U.S. citizen, was not legally separated at the time of death and has not remarried. To qualify, the petition must be filed with the United States Citizenship and Immigration Services (USCIS) or Embassy within two years of the death of the U.S. citizen.
How do I apply?
A widow/widower resident in the Poland or Belarus should contact the Public Liaison Unit of the U.S. Embassy in Warsaw for information on the steps which must be taken to file the petition, form I-360. Those resident in the United States should contact the USCIS office for further information.
You can find more information pertaining to the widow/widower of a U.S. citizen on the USCIS website.