Mill Branch Trail at the intersection with the Collie Ridge Trail in the backcountry of Mammoth Cave National Park

---

If you plan to hike in the backcountry of Mammoth Cave National Park, do not rely on the map that comes with the free park brochure. Purchase the weatherproof map by National Geographic that is available in the Visitor Center book and souvenir store. This map has more detail, and it is going to last much longer than the paper map. I hiked most trails in the backcountry using the National Geographic map, and it’s nearly as good as new.

---

Length:  2.9 miles (one way)
Time:  2 hours
Difficulty: Moderate
Suitable for Horses: Not my horse, but horses do use the trail

The Mill Branch Trail is one of the many backcountry hiking and equestrian trails within Mammoth Cave National Park. It is a 2.9-mile out-and-back trail that runs between the Big Hollow Trailhead and the Collie Ridge Trail. It is possible to combine it with other trails to form a loop, but don’t expect any short hikes in the backcountry. I made a loop starting at the Lincoln Trailhead on the Collie Ridge Trail that utilized 1.9 miles of the Mill Branch Trail and the entire Raymer Hollow Trail, and the hike was roughly 13 miles long.

Mill Branch Trail map (click to enlarge)

This trail report only covers the Mill Branch Trail between the Collie Ridge Trail and the intersection with the Raymer Hollow Trail (1.9 miles as stated above). There is a mileage marker attached to a tree every quarter mile, though some are missing. The 0 marker is at the Big Hollow Trailhead. Since I was hiking from Collie Ridge, the miles counted down as I went. (Note that MB on the mileage marker stands for Mill Branch).

It is also important to know that the route of the equestrian trails in the backcountry are marked with blue blazes. These are usually paint splotches on trees and rocks that you follow like Hansel and Gretel breadcrumbs, though in the Mammoth Cave backcountry the blazes are markers that are nailed to the tress.

Mileage marker and blaze for the Mill Branch Trail in the backcountry of Mammoth Cave National Park

Unlike some of the backcountry trails at Mammoth Cave National Park that are old dirt roads, the Mill Branch Trail is a traditional hiking trail. The general trajectory of the first 1.25 mile is downhill towards the Dry Prong (a creek), though rarely was I aware that I was traveling downhill. Other than a short, 100-foot dip with slopes that have an average grade of 20% both down and out (15% is where strenuous hiking begins), grades typically do not exceed 10%. Overall there are five gradual descents separated by short, level areas on this section of the trail.

Typical terrain on the Mill Branch Trail near the intersection with the Collie Ridge Trail in the backcountry of Mammoth Cave National Park

Being narrow, ticks should be of concern. Some segments of the trail are a little overgrown, and you have no choice but to brush up against vegetation. Whenever you do so, check your lower legs for ticks. I have picked them up on dirt trails with no greenery anywhere near the walking path, but generally ticks are in the vegetation waiting for something to come by. For the record, I did not get any ticks on me during this hike. And by the way, there are briers on the trail as well, so be sure to wear long pants regardless of how hot it is outside.

Starting a quarter mile from the Collie Ridge Trail and continuing for another half mile, the Mill Branch Trail turns into a gully, at some points knee deep. There is plenty of evidence that horses do travel on the trail, so perhaps the gullies have been worn into the soft dirt over the years by the heavier horses. In some places you could fill these with water and have yourself an amusement park flume ride. The trail definitely covers some rough terrain.

Trenches of the Mill Branch Trail west of the Raymer Hollow Trail intersection, Mammoth Cave National Park

The trail gets rocky and rutty about a mile from the Collie Ridge Trail intersection. There are also some patches of mud that have been made worse by horses churning up the dirt (the water may well be horse piss). There is one spot so bad that somebody placed a log across it, and many of the mud holes have hiker-worn side trails around them, but these are often no better.

Rocky terrain on the Mill Branch Trail north of Dry Prong, Mammoth Cave National Park

Typical mud pit on the Mill Branch Trail created by horse travel, Mammoth Cave National Park

At the end of the long descent is the Dry Prong. This is a creek bed that is as wide as a dirt road. I am assuming that, given its name, it is dry more often than not.

Mill Branch Trail crosses Dry Prong in the backcountry of Mammoth Cave National Park

Walk across the creek bed, which is full of ankle breaking rocks, to continue the hike. One hundred yards ahead is the Mill Branch, another creek that was dry when I did the hike. Just before it, the Mill Branch Trail makes a left-hand turn that is very easy to miss. If you get to the Mill Branch, you missed it.

Dry creek bed of the Mill Branch in the backcountry of Mammoth Cave National Park

The reason the turn is easy to miss is because it doesn’t really look like a trail. The telltale sign, however, is the horse hoof prints in the mud between what is otherwise a field of rocks, and not too far down is a blue blaze.

Turn on the Mill Branch Trail just prior to the Mill Branch when hiking east from the Collie Ridge Trail, Mammoth Cave National Park

The Mill Branch Trail begins an ascent not long after making the turn. The climb lasts a tenth of a mile and has an average grade of 11%, so while not considered strenuous, it is steeper than most of what has come before. Making matters worse is the rocky terrain.

At this point, the Mill Branch Trail devolves into chaos. There are rubble rocks, horse-created mud holes a half foot deep, and a few downed trees. Plenty of side trails were cut by previous hikers to get around some of the aforementioned obstacles. I do have to say, however, that this is far from the worst trail in the backcountry of Mammoth Cave National Park. Many are Certified Rotten, not fit for man or beast. I won’t go so far as to certify the Mill Branch Trail as rotten, but it’s close.

The trail gets a little better once past the 1.5 Mile Marker, then, oddly enough, two tenths of a mile later it becomes a dirt road. I could see the Mill Branch down below. There were pools of water in it at this point.

Mill Branch Trail is an old dirt road from the Big Hollow Trailhead until a half mile west of the Raymer Hollow Trail intersection, Mammoth Cave National Park

View of the Mill Branch from above on the Mill Branch Trail in the backcountry of Mammoth Cave National Park

The dirt road section of the Mill Branch Trail does head uphill at a moderate pace for a quarter mile before coming to the intersection with the Raymer Hollow Trail, which was the end of the road for me. Just before the intersection is a tree with a massive burl—the Elephant Man Tree.

Tree with a large burl along the Mill Branch Trail just west of the Raymer Hollow Trail intersection, Mammoth Cave National Park

The turn on the Raymer Hollow Trail is a sharp V-shaped turn to the left. It would be easy to miss if it weren’t for a sign at the intersection.

Intersection of the Mill Branch and Raymer Hollow trails in the backcountry of Mammoth Cave National Park

The Mill Branch Trail continues for another mile back to the Big Hollow Trailhead. I did not hike this section, but I can only assume it remains a dirt road. Based on topographic maps, I do know for sure that the hike continues uphill nearly all the way to the end.

In regards to horseback riding, I don’t ride horses, but if I did, I wouldn’t take my horse on the Mill Branch Trail west of the Raymer Hollow Trail. However, there’s plenty of horse tracks, so people do it, most likely those who want to make a loop with the Raymer Hollow Trail, or from the Collie Ridge, Raymer Hollow, and the rotten part of the Mill Branch Trail as I did. My bet is that the riders who do press on just don’t want to turn back, figuring that things are going to get better just around the corner. From the 1.5 Mile Marker to the Collie Ridge Trail, they don’t. Unless you have a 4-Wheel-Drive horse, it is best to avoid this section of the Mill Branch Trail.

1.5 Mile Marker on the Mill Branch Trail in the backcountry of Mammoth Cave National Park

Back to the Top