> The US has been filled to the brim with cars for decades In the 1970s, I lived in one of the western suburbs of Denver, about a mile from I-70. At night when

> The US has been filled to the brim with cars for decades In the 1970s, I lived in one of the western suburbs of Denver, about a mile from I-70. At night when things were quiet, I could hear individual cars. In the 1990s when I was back for visits, I-70 had the steady hum of continual traffic. There are definitely more cars per household than there were fifty and sixty years ago.