Subway debuted as Pete’s Super Submarines in Bridgeport, Conn., in the summer of 1965, when a Brooklyn-born 17-year-old named Fred DeLuca borrowed $1,000 from a family friend, a doctor named Peter Buck. De­Luca, an aspiring doctor who is now worth $2.6 billion, hoped slinging sandwiches would help him pay his way through medical school.

The duo slogged through several slow years of sandwich-making until, in 1974, they started selling franchises under a new name, Subway. (One theory: The old name, on radio ads, sounded confusingly like “Pizza Marines.”)

In the decades that followed those first shops, Subway franchises have expanded, yeast-like, onto what seemed like every street and strip mall in America. By 2013, Subway was opening 50 new shops a week. Today, Subways serves nearly 2,800 sandwiches every minute, data from industry researcher IBISWorld shows.

Still owned by Doctor’s Associates, the founders’ holding company, Subway has opened inside hundreds of U.S. colleges, malls, military bases and other, less-predictable locations: a car showroom in California, a Goodwill thrift store in South Carolina, a church in Buffalo.

Washington Post national business reporter Drew Harwell examines the troubles facing the ubiquitous sandwich franchise as it nears its 50th birthday.

Read the story