According to the National Conference of State Legislatures, laws regarding cousin marriage in the United States mostly apply to marriage between first cousins, rendering marriage to a third cousin legal. Only 25 states prohibit first cousin marriage under any circumstances.
The National Conference of State Legislatures states that Arizona, Illinois, Indiana, Utah and Wisconsin allow first cousins to marry, but only if at least one person in the union is incapable of reproducing or if either one or both of the couple is over a certain age. Maine allows first cousins to marry if a physician's certificate of genetic counseling is obtained. Marriage between first cousins is legal in Alabama, Alaska, California, Colorado, Connecticut, the District of Columbia, Florida, Georgia, Hawaii, Maryland, Massachussetts, New Jersey, New Mexico, New York, North Carolina, Rhode Island, South Carolina, Tennessee, Vermont and Virginia.