For a brief time, Milwaukee exported more wheat than any other port in the world. The Grain Exchange was closely linked with the early commercial history of Milwaukee. It was a lake port near vast acres of wheat, and it became one of the chief national markets for the trading and inspection of grain.

The Milwaukee Grain Exchange found a home in this Chamber of Commerce building, but the Grain Exchange as a business enterprise predates this particular building. In the 1860s, the Grain Exchange invented and utilized the very first trading pit. Its prices were quoted in grain centers around the world. And the Exchange owned an early baseball club - the Cream City Base Ball Club.

So it was with a great flourish that the Exchange moved into its lavish quarters in 1880. At precisely three o'clock on November 18, 1880, the new Chamber of Commerce building was dedicated. Milwaukee's elite turned out for a celebratory banquet across the street in the Newhall House, then Wisconsin's largest hotel.

But the fortunes of the Grain Exchange shifted rather quickly just as it moved into its new building. In 1881, Minneapolis and Duluth both established exchanges. Together, this diverted some of the plains crops away from Milwaukee's exchange. As railroads spread further west, Milwaukee's lake shipping business declined and Chicago's status as a regional railroad hub ascended.

When a devastating cinch bug infestation chewed its way through Wisconsin wheat fields, most farmers switched to dairy cattle to make ends meet, and the Exchange further lost business.

The Exchange took another blow during the global grain slump of the Great Depression. The papers in the early 1930s were full of dire news. "The seaboard is glutted with grain, with Europe showing little desire to buy," reported a Cargill Grain Co. spokesman in 1930. Another headline blared, "Nation's Corn Crop Lowest in 29 Years."

With grain in a slump, the Chamber of Commerce looked to branch out beyond the Grain Exchange and began selling securities in addition to wheat. It happened in fits and starts, but in the spring of 1931, the Chamber of Commerce announced the launch of the Milwaukee Stock Exchange. The launch was successful, but neither the Grain Exchange nor the Stock Exchange ever enjoyed the same prominence of the late 19th century.

In 1934, the Chamber of Commerce sought out a new home for its operations and moved out of the grand building. The building was renamed the Mackie Building, after Alexander Mitchell's nephew.