It may have centered on NYC, or just mentioned it. This also may be from older than 1970. It went roughly like: one morning, the laws of probability collapse. The highway system, which is scaled for 'normal' traffic patterns, can't handle it when EVERYONE on Brooklyn suddenly each for their own very individual reason decides to drive to Ocean Beach. That kind of thing.
If there was a longer arc with a real story and resolution, I don't recall it.
Ring any bells?