The Aspen Trail (Trail 21) begins at the second parking lot in the park (just past Dragonfly Pond). It descends to the southeastern most edge of the park and then climbs back to the parking lot.
From the parking lot, head south. Multiple trails intersect here: the School Pond Trail (Trail 2)
, the Ranger Ridge Trail (Trail 3)
and connections to Stoner Mill Trail (Trail 23)
. Keep left to follow the Aspen Trail (Trail 21) as it descends to the eastern edge of the park.
The trail then turns south along the park's border. The elevation profile does not capture the multiple steep descents and ascents along this portion of the trail. Grades of about 20% occur along this section of the trail, making it one of the more challenging trails at Mueller.
At mile 2.2, the trail begins a steady climb, then turns west for about a mile before it descends back to the trail-head.