Burger King is back in second place.
The chain regained its status as the No. 2 U.S. fast-food hamburger seller last year, a spot it lost to Wendy's in 2013, according to researcher Technomic Inc.
Burger King's domestic sales rose 1.6 percent to $8.64 billion in 2014, while Wendy's Co.'s fell 0.4 percent to $8.51 billion, the data show. McDonald's Corp. had $35.4 billion in U.S. sales last year.
To lure more customers, Burger King has been advertising limited-time offers and brought back cult favorite Chicken Fries at the end of March. Wendy's, meanwhile, is pushing crispy chicken sandwiches and recently began selling Honest organic green tea to attract younger diners.
Burger King has become "increasingly competitive with McDonald's by broadening their menu and focusing on value," said Darren Tristano, executive vice president at Technomic. Wendy's has moved to higher prices and more premium foods, which may deter lower-income consumers, he said.
Burger King's domestic same-store sales jumped 6.8 percent in the most recent quarter, fueled by its Spicy BLT Whopper and two-for-$4 croissant breakfast sandwiches. Wendy's North American same-store sales increased 3.2 percent in its latest quarter.
Before being unseated by Wendy's in 2013, Burger King had been the No. 2 chain since at least 1972, according to Technomic. Sonic Corp., the drive-thru chain, is ranked No. 4, while Jack in the Box Inc. is No. 5.
Burger King is owned by Restaurant Brands International Inc., which also owns the Tim Hortons chain.