|New York, under construction lot-by-lot.
(Source: New York Historical Society)
For the past 70 years or so, much of what we have built in the US has been of the large, "master planned" variety of development. Large areas of dozens, sometimes hundreds, of acres are all laid out and designed at once, and built out by a single builder or a handful of builders working off of a coordinated design. Once they are built out, these areas change very little over time. During the era of suburban expansion, residential subdivisions, garden apartments, office parks, and shopping malls all fit into the master planned category of development.
When New Urbanism rose onto the scene, many of its early and iconic projects, such as Seaside and the Kentlands, were also large, master-planned developments. Unlike their sprawl counterparts they were walkable, compact, mixed-use, and awesome... but they were still large and master-planned.
This feels normal to our generation, but historically this is an anomaly. Prior to World War II, and going back for millennia, most development was not of the large-scale, master-planned variety. Rather, most cities and neighborhoods were built lot-by-lot, by dozens or hundreds of land owners and developers. Even when the street and lot pattern was laid out all at once by a city (as in New York's grid of 1811) or a railroad company, the lots were auctioned off to individual parties who carry out the task of building on their own, one by one. In such urban settings, the development of the place is never complete, and many lots will be developed and redeveloped over the years to meet the changing needs of their owners and the market as I discussed in a previous post called Small Lots and the Evolution of the City. Some have referred to this kind of development as Incremental Urbanism. I like that term, and will use it on this blog.