As my previous post, Minimum FAR for Walkable Urbanity & Westerville, Ohio discussed, there is a minimum floor for walkable urbanity; an urban situation where density reaches critical mass allowing all of the Jane Jacobs virtuous effects of urbanism to form: independence from the automobile, more eyes on the street, etc.
Below is a historical survey of four different Columbus, Ohio area residences and one Brooklyn, NY residence. These diagrams are figure-ground relationships illustrating the lot, setbacks (front, side & rear) and house size.

1. East Coast Urban Lot
2. Midwest Urban lot – German Village
3. First Suburbs – Huber Ridge
4. Reagan Suburbs – Dublin
5. Midwest Exurbs – Dublin

Note how large the lots have become throughout the years, and the location of the house in context of the lot itself.
Upcoming diagrams will argue that the large front yards of newer developments are both wasted space and are a principle reason why Suburban landuse isolates their homeowners.