Look at photos of restored old-west towns. There were often apartments and flophouses. They often started as a large tent and as money came in, so did the permanentness of the buildings.

Think about the economics of the old west towns. Towns tended to pop up at places were settlers, farmers, miners, trappers, other, would come together to trade. People would move to a town before looking for their farm, mine, or whatever. Some would stay in town finding work there. For many it was cheaper to rent an apartment, quite often just a room in a larger house, than it was to maintain a whole house until they were married.