Updated 10:41 p.m.
The Associated Press called the race for Ratcliffe, with 66 percent of precincts reporting. He was leading Hall 52 percent to 48 percent.
Hall's defeat means that there will be no World War II veterans serving in Congress beginning next year. The only other remaining veteran of the war, Rep. John D. Dingell (D-Mich.), is planning to retire.
With his win in the runoff Tuesday night, Ratcliffe, 48, is all but assured to represent the 4th Congressional District of Texas, a Republican stronghold that stretches from the far eastern suburbs of Dallas to the Louisiana border.
In a statement Tuesday evening, Ratcliffe thanked Hall for "serving us admirably and wish him the best moving forward."
"I entered this race because I want a better path for America than the one that we’re on right now," Ratcliffe added. "Tonight, the voters of this district confirmed what I’ve been hearing on the campaign trail for the last six months."
Ratcliffe is a former U.S. attorney and mayor of the town of Heath, Tex. More recently, he's worked in the Dallas office of a law firm run by former attorney general John D. Ashcroft and served as an aide to Republican presidential candidate Mitt Romney as part of a transition team established before the 2012 elections to begin vetting potential Cabinet and senior government appointees.
Hall first won an election in 1949 and was elected to Congress in 1980 as a Democrat. He switched parties in 2004 and has maintained a conservative voting record in recent years. Hall had vowed in the past few months that he wanted one more term in Washington to see the end of the Obama presidency and to help elect a Republican to the White House.
Hall was forced into a runoff after winning just 45 percent of the vote in a March primary. Both candidates have touted endorsements from an array of conservative organizations and activists. While Ratcliffe enjoyed the support of Tea Party Express, the Senate Conservatives Fund, the Club For Growth and conservative Texas state lawmakers, Hall gained the backing of the National Rifle Association, dozens of his Republican congressional colleagues, former Rep. Ron Paul (R-Tex.), former Arkansas governor Mike Huckabee, and the singer Pat Boone.
The Hall-Ratcliffe race was one of the most closely watched contests in a series of runoffs Tuesday in Texas.
In the state's 23rd Congressional District, Republicans selected former CIA operative Will Hurd to challenge first-term Rep. Pete Gallego (D-Tex.) in the Lone Star State's only competitive swing district this cycle. The district is majority Hispanic and includes roughly 800 miles of the U.S.-Mexico border, the longest stretch in any House district.
Hurd defeated former Republican Rep. Quico Canseco, who lost a competitive race to Gallego in 2012 and had faced Hurd in a similar 201o runoff election. Canseco entered this year's race late, allowing Hurd to build an early fundraising lead.
In the state's 36th Congressional District, another safe Republican seat, Brian Babin was leading Ben Streusand to succeed retiring Rep. Steve Stockman (R-Tex.).
Texas Democrats also chose wealthy dentist David Alameel to face Sen. John Cornyn (R-Tex.) in November. Alameel, favored by party leaders, defeated underdog Kesha Rogers, who supported impeaching President Obama. Cornyn is heavily favored to win a a third term.
Sean Sullivan contributed to this report.
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