The Longleaf is a southern Mississippi paved trail 44 miles in length. I rode the trail from the gateway at MM 3 to MM 22. The gateway at MM 3 has a manned visitor center and available bike rentals. This is located at the University of Southern Mississippi, Hattiesburg, MS. I entered the trailhead from 4th street only to find myself on university property. DO NOT PARK HERE. You may find your car towed. Trailhead parking is a smaller lot behind the university lot (31.332856, -89.330232) accessible from Northwood Drive.
Petroleum-propelled vehicles are not allowed. Golf carts are allowed with a permit. Horses have a separate, parallel trail along portions of the Longleaf. I found the trail to be smooth, flat, wide and straight with few road crossings. Most of the trail has a nice tree buffer providing shade and screening of adjacent properties. Trailheads generally had water fountains, flush toilets and bike fix-it stations. Additional rest areas with benches dot the trail.
Additional information about the trail may be found here. Scroll to the bottom of this page for a video of my ride.