Bad traffic was mostly limited to a few large cities such as LA then. In most of the US, it was not nearly as bad. It was also believed that traffic was a fair

Bad traffic was mostly limited to a few large cities such as LA then. In most of the US, it was not nearly as bad. It was also believed that traffic was a fairly minor infrastructure problem that could easily be resolved by widening the highways, adding a few more lanes here and there. (Turns out that when you add lanes, it just causes that many more people to drive on that road, but this was not yet widely apparent at the time.)