Where do people bicycle?

Where do people actually bicycle? Planners, non-bicyclists, and bicyclists themselves often have misconceptions.
Family bicycling in Jefferson City

Many studies have been done and they all come up with similar results. Here is a summary of the results from a typical survey, by William Moritz (1998):
Minor roads, no bicycle facilities: 45%
Major roads, no bicycle facilities: 32%
Roads marked as bicycle route: 6-7%
Roads with a bicycle lane: 6-7%
Multi-use trail: 6-7%
Off-road/unpaved facilities (like mountain biking trails): 4%
Sidewalk: 0.3%
A similar study by the National Safety Council of "typical" college-age bicyclists--ie, those who bicycle for practical reasons rather than that they are avid bicyclists--found that 71% of their riding is on the street with traffic.