Long Island Greenbelt Trail (NY)
The Long Island Greenbelt Trail runs about 32 miles from Heckscher State Park to Sunken Meadow State Park. Evolution of the FKT is documented on the old site. Barney Fortunato ran this 32-mile route a couple of times with a best time of 4h41m15s on July 25, 2015. Others have run it, but we know of no faster completion.
Here's a link to the Long Island Green Belt Trail Conference (maps & information).