Could it be---Alexandria to Roslyn in DC? or The Bike and Hike Trail in Cleveland that opened up in 1972? Or the trail that Follows Chicago's waterfront that was old railroad wharves on Lake Michigan that was done in the 1960s
Through the years the prosperity of the [New York and New England Railroad] rail line ebbed and flowed, but by 1931 passenger service had run its course. Fifty years after it began, it was discontinued. Freight traffic, including the regular milk trains, hung on through the 1930s but finally fell victim to the depression. The line was abandoned in 1939.http://www.ct.gov/deep/cwp/view.asp?a=2716&q=434808" onclick="window.open(this.href);return false;
In 1943, four years after the abandonment, a 10.3 mile section [from Naugatuck to Southbury] was purchased and gifted to the State by Dr. Charles L. Larkin. His gift was for the express purposes of establishing a state park and bridle trail – recreation for the very animals the railroads worked so hard to keep off the tracks 60 years earlier.