We've watched these changes happen, of course. From the aging houses in our grandparents' neighborhood (the one they lived in before moving to an Arizona active adult community) to the new homes in our own just-developed neighborhoods, the American house has evolved a great deal.

"These Old Houses," a new report by the U.S. Census, shows exactly how different things used to be. Looking only at homes built before 1920 and after 1989, the study compares the characteristics of homes erected decades apart, providing a snapshot of how American families, communities, and housing expectations have changed.

The bulk of these old homes (the ones built before 1920) stand in the Northeast, a region that also has the country's lowest supply of housing. Second in line in terms of housing age is the Midwest, followed by the new-construction heavy South and West, which have seen much of the recent building boom.

One finding differentiating old and new homes will come as no surprise to anyone who sparred with a sibling over the lone bathroom in a quaint, older home: 46.2 percent of homes built before 1920 have only one bathroom and no half-baths. In contrast, that's true for only 6.3 percent of new homes (those constructed in 1990 and after).

There are a few other differences between old and new. Garages, nonexistent in 1920 due to the rarity and cost of automobiles, are now commonplace, especially in the Midwest and West, where more than 90 percent of new homes include a garage. Homes used to be smaller -- a median of 1,862 square feet for single-family detached homes built before 1920, compared to 2,161 for those constructed in the 1990s and after and they also used to be taller. More than 80 percent of old homes in the Northeast and 63 percent of old homes in the Midwest include three or more stories, a feature now replaced by one-level living. According to the report, there are nearly 4.9 million "new" one-story homes, more than five times the number of one-story pre-1920 homes (934,000).

Luckily for builders, new housing often reports higher values, with new homes selling for $28,000 more than existing in January 2004. Old houses don't have all the design features people are looking for now, says Michael Carliner, an NAHB economist. Perhaps it's those lone bathrooms. Each additional full bathroom can add 24 percent to a home's selling price according to research recently done for the National Association of Realtors by two Florida State University professors. current sales, expected sales, and buyer traffic.