The 70-Year Club is nothing if not diverse. (Pfizer, maker of Viagra, meet Hormel, maker of Spam.) But a few themes emerge from a closer look at these corporate endurance athletes. Among them:

It’s an automotive nation. Six of the top 10 companies of 1955 either made cars or pumped the oil that fueled them. General Motors was No. 1; Chrysler (now part of Netherlands-based Stellantis) was No. 6. Ford Motor didn’t report revenue publicly at the time, but trust us, it was big. In the oil patch, Exxon was No. 2 and Mobil was No. 9. They merged in 1998; this year Exxon Mobil is the only Class of ’55 member in the top 10, at No. 7.

Big Food is un-disruptable. Software eats the world—but software engineers still have to eat. The food and tobacco category accounts for 10 members of the 70-Year Club, more than any other sector.

Know when to merge. In volatile industries, consolidation can be a life preserver. That’s been especially true in aerospace and defense, where Boeing, RTX, and Lockheed Martin have all reshaped themselves over the past few decades through M&A.

And know when to split up. Storied conglomerate General Electric was No. 4 in 1955 and was a top 10 company as recently as 2015. But its sprawling range of businesses eventually contributed to its steep decline. After numerous sales and spinoffs, GE (now ranked No. 56) mostly sells jet engines, and investors love it. In 2019, Class of ’55 alum DuPont split into three companies; today, they’re all on the Fortune 500.

A version of this article appears in the June/July 2024 issue of Fortune with the headline, “Meet the Class of 1955.”