Here's something to consider:
In Tulsa, in 1966, we had a thriving, densely populated city that was able to provide services to it's residents. Downtown was not characterized by "deteriorating tenements." It was an active and thriving city center. It had schools, shops, houses, apartment buildings, business headquarters, theaters, civic clubs, grocery stores, etc, etc, etc.
In 1966, however, Tulsa annexed so much land, it tripled its size overnight. It went from 57 square miles to 175 square miles. Suddenly (and ever since), the city has struggled to provide basic services and infrastructure to it's enormous land mass. As a result, the city has been under pressure to develop anything it can in sprawling areas, in an attempt to grab essential tax dollars.
Where development had previously progressed in an orderly and logical manner, it now was at the mercy of developers and builders who wanted to make a quick buck.
So, yeah, folks were buying cheap land and big lots far from the city center. A growing array of suburban living options became available. As a result, you had to have a car. (As people and housing were dispersed over a larger and larger area, it became more difficult to provide working transit.) With all the wide open space, it was easier to build stores on big lots and strip malls...which, naturally catered to the car. And, since everyone needed a car for everything, it's no surprise that folks started shopping at their shiny, new stores (located miles from home, but including nice, big parking lots).
However, my point is that urban planning decisions (or the lack thereof) drove (pun intended) our current, car-dependent way of life.
If you're interested in the history of Tulsa's development, there's a fascinating paper on the City Council website, written by Jack Blair in 2004: "A History of Tulsa Annexation."
Tulsa's leaders made a lot of mistakes in the '60s, but I don't think the 1966 annexation was one of them. Low-density suburban development was going to continue, driven by many other forces -- some political, some societal. The big annexation ensured that a lot of that development happened within Tulsa's city limits, so we continued to capture sales and property tax revenue. It did, of course, also make us liable for providing infrastructure and services to that vast area. If those areas had developed at the same density of the pre-1966 city, we'd have been better able to finance that infrastructure and those services.
Prior to 1966, Tulsa would add new subdivisions to the city as they were built and as the developers requested annexation. One of the arguments for a large annexation was that new developments would be built within the city limits and under the city's building and planning codes. Another argument was that annexation was a defensive move, as suburban municipalities began to annex fence lines that would constrain Tulsa's potential growth. (I'm not sure why Tulsa opted for full annexation rather than fencing future growth areas.)
It's funny: Planning documents from the late '50s expected that the City of Tulsa's population would approach one million by the end of the 20th century. The planners seemed to expect new development at the same density.
Tulsa's urban renewal began in the mid-60s as well; DTU leaders were talking about clearing out the old commercial blocks between the tracks and 3rd as early as 1957. The radial expressway system was mapped out in '56.
Downtown decline was going to happen and was already well underway by 1966. The problem is that the actions Tulsa took then to try to stem that decline hindered and are still hindering the recovery process. Those American cities that didn't ring their downtowns with expressways, required historic preservation, were selective about demolition, and avoided the use of superblocks and pedestrian malls were better positioned for downtown revival.