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I have long admired the trip and distance data collected sporadically by the National Household Travels Survey. Not because of its fine scale (it is national only) or because of its annual updates (irregularly between 5 and 10 years), or even its consistent methodology (It, like the census, has shown a nasty drift in survey methods and assumptions between surveys).

What I admire about the NHTS is that it surveys all the modes (traffic, transit, walking, and biking, along with boat, and air trips.. That is not to say it surveys them with perfect accuracy. It surveys people after the fact, who may or may not exaggerate or misremember their travel use in even the recent past. That is also not to say that it achieves the grail of transportation surveys: the “tour”. Many of us walk to our cars before parking them near our destination where we might walk some more to get to our destination. Transit users always have to get to their stop or station, be it walking, biking, traffic, or a different mode of transit. Only the luckiest Brooklyn Heights commuter walks right from their front door to the ferry and thence to their work on Wall Street. They might need a CitiBike to complete their trip.

MY final frustration with the NHTS has been its evolving acceptance of Walking and Biking as modes. Though they do a good job of delivering 1995, 2001, 2009, they don’t deliver the 1989 or 1983 results in anywhere near such a convenient form. Which is just as well, because their attitude towards walking and biking have been evolving from invisible to minorities.

But then it occurred to me to look at the reports to see if they had any information on biking and walking before 1995. It took some hunting, but I was able to get some numbers of trips by walking and biking among all the less useful summary tables. Assuming that the average walk distance was 0.5 miles and the average bike distance was 1.3 miles, I was able to estimate the total miles traveled for these unsung modes. I based those estimates on the the trip distances from the three NHTS dates I did have trip numbers and distances for: 1995, 2001, and 2009.

So here’s the longer term trends in miles per capita for not only traffic and transit, but also biking and walking, expressed in miles traveled per capita.


Notice the downturn in traffic miles traveled down to 1990 levels, the uptick in transit use since 1996, and the climb of biking and even walking from their lows in 1991. 1991, by the way, was the first year that federal transportation policy shifted to acknowledge walking and biking as anything but a local concern.