I Lan Park trailhead, Tomahawk Creek Trail -- Leawood, KS

Start a run along the Tomahawk Creek Trail from here, heading north.  The trail never makes you cross a road, and it's mostly tree-covered.  (Essential in the summer!)  Creek-adjacent, makes it easy to know where to turn.

Update: you can also start from the Leawood Aquatic Center and either run south to I Lan park, or north which takes you across the state line, for bragging rights.