In the United States immigration petitions are processed through the United States Citizenship and Immigration Services (USCIS), an agency within the Department of Homeland Security. Immigrant visa numbers are issued through the State Department in preference and prioritization systems once the USCIS has approved a petition. Most foreign nationals file attain immigrant visas through one of two avenues, immigration through family or immigration through employment. In order to be eligible for immigration through family, an immigration petition and affidavit of support must be filed by a relative who is a U.S. Citizen or lawful permanent resident. In order to be eligible for immigration through employment, the foreign national must be sponsored by a U.S. employer who has attained a labor certification and submitted an immigration petition on his behalf. Other, less common avenues to U.S. immigration include the Diversity Lottery Program and immigration petitions for Special Immigrants, including persons who have worked for or on behalf of the U.S. government and religious workers.