From Associated Construction Publications website:
The 225-mile-long Katy Trail has the distinction of being the longest developed rail-to-trail conversion project in the nation. It is estimated that approximately 350,000 people annually use the trail, which runs from St. Charles to Clinton.
Disclaimer: All project trails listed on TrailLink.com are in various phases of development and may not be open for public use. Rails-to-Trails Conservancy does not manage any trails listed on TrailLink.com. To learn more about the current status of trail development, please look in the "Related Links" section below to find contact information for the local organization or agency responsible for trail management.