Out of the millions of houses built in the United States from the early 1900s through the 1970s, the vast majority qualify as a classic builder-driven house type. American foursquares dominated the outskirts of cities in the late 1800s and early 1900s, only to give way to the beloved bungalow of the 1910s, '20s, and '30s. The Cape Cod cottage and the center-hall colonial, both revivals of house types built for centuries, enjoyed pre– and post–World War II popularity. During the 1950s, '60s, and '70s, the ranch house and the split-level muscled in and redefined the look of the suburbs. Each of these six types reflects the idealized lifestyle of its era, and each one has its own idiosyncrasies. Buyers are drawn by their locations, their detailing, or their affordability—and turned off by their modest kitchens, baths, and master suites. For better or worse, these houses provide a vast canvas of potential remodels for today's architects. And the quality of their renovations affects the built environment just as much as brand-new development.