Taco Bell pushed past Burger King in 2017 to become No. 4 restaurant chain in the U.S., with $9.8 billion in sales to BK's $9.3 billion. And with No. 3 Subway's sales sagging, Taco Bell could jump into the top three in 2018, according to research firm Technomic. The rising popularity of Mexican-style cuisine, Taco Bell's low-priced offerings, and the misfortunes of Chipotle Mexican Grill likely helped Taco Bell.