Flat gravel road, basically no traffic.
The best parking area from the south, is located at the boat launch on the west side of the river near Highway 18 (see the parking icon to the southwest). To reach the start of the levee, simply pedal east on Highway 18, and then take the first left on Macey Road.
This is a great level gravel road that travels along the St. Francis River to the Missouri State Border. There's almost no elevation change and the surface is smooth, so riders can enjoy an unchallenging pedal.
Once on the levee, you'll be on 100% gravel. You can ride the road with any bike comfortably. Along the way, there are some connectors that lead to other county roads, however most of these will hold water if it has rained recently. You'll also see yellow numbered mile markers on the levee which can assist in letting you know how far you've traveled if you are not using GPS or the MTB Project mobile app.
Once you get to the Missouri state line, you could exit the levee on the State Line Road to take a different route back to where you started (Missouri apparently does not mow the levee on their side. It is ride-able, but in the summer time you'll be riding a narrow path in tall grass). Otherwise, turn around and head back the way you came.