The "Summary of Travel Trends: 2001 National Household Travel Survey" (Dec, 2004) is full of data and findings to occupy urban researchers for some time.
In spite of years of "Smart Growth", 2001 was the first year that there were more vehicles per household than licensed drivers per household (1.89 vs 1.77).
2001 was also the year that saw a reverse in previous increases in worktrip speeds. Yes, the average commute was getting faster between 1983 and 1995 (covering three previous surveys). No more.
Was Smart Growth to blame? All we can say for sure is that it didn't help.
We do know that the 1995-2001 period was a time of rapid income growth. Not only did people have greater access to private vehicles but as people become wealthier, they travel more -- just as they consume more of everything.
We are back to the old story. If policy makers want to "do something" about auto travel, they have to price road access and parking correctly. Nothing else works. Most U.S. policy makers are, however, bent on trying anything but proper pricing. Not smart.