From the Trail:
The parking lot runs alongside the trail, underneath highway
55. You'll know it when you see it.
Take I-55 to Reavis Barracks (exit 199), which is north of 270
and about 10 miles south of downtown. Go east on Reavis
Barracks for 1 block, to Union Road. Go right (south) on
Union about 3/4 mile.
Caution: Green Park Road crosses Union from the east about
0.25 mile from where it continues to the west (see map above). If you see
a gas station on the far corner of the intersection, you'll know
it's time to turn right onto Green Park.