The roster continues to reflect the ongoing evolution of the American economy. From a developing economy that drew heavily on commodity production and extraction — American Sugar, Standard Oil and U.S. Steel — the Dow 30 membership tracked the rise of manufacturing through the middle of the last century — Goodyear, Boeing, General Motors — and the more recent emergence of an economy driven by information, finance and services industries: Visa, Microsoft and Verizon.
If past is prologue, the Dow roster will look very different in 25 years. Of the 30 current stocks, fewer than half were members in 1989. Only five have maintained membership for 50 years, and only one — General Electric — has been a Dow stock since the index expanded to 30 companies on Oct. 1, 1928.
By 2039, some of today's iconic companies will likely have faded away like an old Kodak photo, or closed up shop like a Woolworth's lunch counter.
And there will likely be whole new industries whose contributions to the U.S. economy will be represented on the Dow. In 1989, big-box retailer Home Depot had just opened its 100th store. Cisco Systems — not yet a public company — was making something called a network router that few people outside the IT departments had ever heard of.
So while you can expect the list to take on an entirely new set of names, it's difficult — if not impossible — to predict what they'll be.
Market-cap data was provided by the Center for Research in Security Prices at the University of Chicago Booth School of Business. The Dow 30 roster, including the dates of entry and departure from the index, was provided by S&P DJ Indices.
Correction: This story was revised to correct that the DJIA expanded to 30 stocks 89 years ago.