My house is made of brick. All of the houses in my neighborhood are made of brick too. There is a lot of clay in the Mississippi Valley. The rivers and streams that trickle into the Missouri River collide with the Mississippi, and hundreds of millions of years of sediment erosion deposit right underneath our city. In the 19th century, clay was accessible, abundant, and everywhere. Clay is a naturally occurring material composed primarily of fine-grained minerals. When wet enough, it has almost doughy plasticity and will harden when dried or fired. Our clay was used for everything from sewer pipes to furnaces, but mostly it was used to make bricks. To turn clay into a brick, it has to be collected, tempered, shaped, and fired in a kiln. A kiln is made from the same clay as brick, so early Saint Louis brickmakers could integrate production by setting up brick processing sites on location with clay mines. The tragic fire of 1849 destroyed most of the wood-built downtown but ultimately created the local brick industry. After the fire, brick construction was a necessity, and the already growing demand doubled. By the 1850s, Saint Louis brick was an establishment with veins as deep in the ground as the clay.