"There were huge clay deposits in there and so that really made it possible to create brick on site. Then the other impetus for this is the Great Fire of 1849 which burned down really the entire St. Louis downtown and led to the passage of ordinances that really required that more construction be brick," said Dr. Robert Archibald.
At the industry's peak between 40 and 50 companies were making brick in St. Louis. Because the clay was such high quality it could also be used to pave streets and make decorative terracotta bricks. This was a particular specialty of St. Louis' large Italian community.
Another advantage St. Louis had was the clay used for making bricks sat below a layer of coal that could be used to fire the kilns. Eventually the supply of both ran out. But today thanks to demand for high quality "salvage" brick St. Louis is still in the business. St. Louis is now exporting bricks from demolished homes.