Some houses are custom-designed by an architect, for a specific site. But most houses weren’t built that way. During the 20th century, many houses were built from plans that the owner or builder purchased from a catalog. Some houses came as “kits,” with plans and a complete set of building materials cut to size and ready to assemble.
If your house has a twin next door, or if you’ve seen other houses around town that look like yours, it’s possible that the builder purchased a plan or kit by mail order. Some catalogs for these plans and kits have been digitized and are now available online. The library also has books with old mail-order floor plans in them.
These websites show exterior views of each house (some in color), floor plans, and prices. Since most mail-order house companies also sold cabinetry, fancy trim, plumbing and lighting fixtures, and furniture, you can sometimes get an idea for popular interior design of the period as well.