Democrat Kyrsten Sinema has been elected to represent a new Phoenix-area district, becoming the first openly bisexual person to serve in U.S. Congress.
Sinema's victory came in a year when three states approved gay marriage, and at least five openly gay Democrats were elected to U.S. House seats.
Tammy Baldwin, a Wisconsin congresswoman, also became the first openly gay person elected to the U.S. Senate during last Tuesday's election.
Sinema had a narrow lead on election night that made the race too close to call, but slowly improved that advantage as more ballots were tallied in recent days.
Her 6,000-vote edge officially earned her the win over Republican Vernon Parker.
Parker, who took the national stage briefly in September when he gave the GOP weekly address, was criticized by Democrats as a tea party radical.
Republicans countered saying Krysten Sinema, 36, was too liberal for the newly created district and doesn't understand stay-at-home moms.
Her victory ensures that Democrats will gain at least one seat in Arizona's congressional delegation. Republicans entered the election with a 5-3 advantage.
The new census added a ninth seat in the state, and he delegation is now split 4-4, with Democrat Ron Barber barely leading Republican Martha McSally.
That Tucson-area district was vacated by retiring Rep. Gabrielle Giffords.