To the untrained pizza palate, the difference between Pepe’s and Sally’s “apizza” is not immediately apparent. (Apizza, according to Bob Consiglio, Sal’s son and one of the owners of Sally’s, is a New Haven term based on the Neapolitan accent of early immigrants to the city.) Both restaurants’ pies have thin crusts and are charred at the edges. Frank Pepe’s is famous for its white clam pie. Sally’s signature pie is its original tomato pizza, topped with a sprinkle of grated Parmesan.

Pepe’s and Sally’s were among the first pizzerias in the United States and helped establish New Haven as a pizza destination. “These are the two institutions that really define New Haven,” said William F. Dow III, a prominent criminal defense lawyer in New Haven and a frequent Pepe’s customer.

Devotees also include alumni of New Haven’s other famous institution, Yale University. Few students have graduated from the Ivy League university without having eaten at least a slice or two.

“It’s very hard to talk about going to Yale without having Pepe’s or the Spot or Sally’s come up in a conversation,” said Mr. Zagat, a class of 1966 Yale Law School graduate who studied over pizza with his wife and law school classmate, Nina Zagat.

After Sal Consiglio died in 1989, his wife, Flora, ran the business along with their sons, Rick and Bob. When Ms. Consiglio died three years ago, she left Sally’s to her sons and their sister, Ruth. Shortly after, the siblings started getting calls from people interested in buying Sally’s. After years of making sauce and kneading dough, the siblings decided to sell.

The restaurant was never formally put on the market, Bob Consiglio said. Instead, the Consiglios invited bids. By spring 2014, they had half a dozen offers, including one from their cousins at Frank Pepe’s. “We felt if they were going to sell, we could keep it in the family,” said Gary Bimonte, one of the seven cousins who own the Frank Pepe’s restaurants. “We just know how hard they worked all these years.”