The Catoctin Trail runs about 28 miles from Gambrill State Park through Cunningham Falls State Park and almost to the Pennsylvania border. After a detailed planning session over coffee at Frederick Coffee Company and Cafe, Carl and I decided to do the southern-most 5.7 miles from the Frederick Watershed trailhead down to Gambrills Park.
We did this stretch in the opposite direction years ago, but Carl's law definitely applies: everything looks different when you walk in the other direction. Which may have been derived from "walk a mile in the other guy's moccasins" or it just may be that we've reached that age where we just don't remember the previous hike, anyway.
This route has a bit of up and down to it, but the first six miles don't feel as strenuous as it looks in the topo profile above. We've had a very wet summer this year, so the streams were gurgling and the vegetation was pretty lush.
After a few crossings of "serenity-now" kind of creeks, we reached the junction of the Gambrill's Yellow trail and followed that back to where we had left my car, probably shortening the overall length from 5.7 miles down to 5.5 or so.
Over the years we have now done various hikes that cover the southern 21 miles of the Catoctin Trail, probably time to do the northern 7-mile section.