Before there were roads connecting the Atlantic to the Pacific and Mexico to Alaska, you could buy goods delivered via railroad freight and/or the U.S. mail. This was more than a century before the Internet, all courtesy of the mail-order catalogs of the Montgomery Ward and Sears & Roebuck companies. It was the Amazon of yesteryear.

Whether you’re a small investor or a company CEO, or neither, monitoring the daily Dow Jones Industrial Average is your way of keeping tabs on the pulse of the nation’s business health, and that’s certainly everyone’s business.