The US population grew by almost 100 million over 30 years, so anything that people do, such as drive cars, is going to increase along with an increase in the number of people.

The neighborhood in which I now live did not exist when I was a child: the area was prairie land at the time. So in that sense, there has been an increase in traffic. Nonetheless, the car traffic in my current neighborhood is no greater than the car traffic in my childhood neighborhoods. The children in this neighborhood are not beset by cars. And there were no children living here when it was an empty prairie, so things haven't gotten worse for them.