Cougar Mountain has seen lots of history over the years, and some remnants of it remain in the form of logging roads, mining railway beds, mine shafts, and the old Nike missile site. Aside from that, it's also a peaceful wildlife area amid the suburban eastside bustle, criss-crossed with trails of various sizes and slopes. The park is a favorite for groups and families that want to get out in the wilderness and see some history, but not travel too far.
Some trails are restricted to hikers only, so pay attention to signs; however, equestrian trails loop their way throughout the park, so you won't miss much territory. It's particularly important to stay on the maintained trails, though, as sinkholes from old mine shafts are continually forming in this area, and the weight of a horse could make the difference. Warning signs tell about existing dangers, and should be taken seriously.
There are officially three trailheads that are open to equestrian use, but the Red Town Trailhead parking doesn' t have much room for horse trailers, so only the Sky Country and Anti-Aircraft Peak trailheads are listed below. The Sky Country trailhead has the most trailer space.
To Sky Country Trailhead: From I-90, take Exit 13 and drive south on Lakemont Blvd SE for 2.5 miles. Turn left on SE Cougar Mountain Way and then right on 166th Way SE (the main road will veer left at this point with a big left-pointing arrow sign which makes a good landmark). Follow 166th to the gate at its end (0.7 mi). On the right is the Sky Country Trailhead parking lot; follow the signs for the horse trailer parking area at the back.
To Anti-Aircraft Peak Trailhead: From I-90, take Exit 13 and drive south on Lakemont Blvd SE for 2.5 miles. Turn left onto SE Cougar Mountain Way. Follow the double yellow line (the road will first swing left and become 168th Pl SE and then right to become SE 60th St). Turn off 60th St uphill onto the dead end road, SE Cougar Mountain Dr. The road will change to gravel - at the end is the trailhead. Trailer parking is a gravel lot on the left across from the turn into the car parking lot. Watch for pedestrians & other trail users on the last mile of this road.
Length: 12 miles of equestrian trails (more for hikers)
Surface: dirt, gravel. Some sections can be muddy after rainy weather. Some steep parts, particularly to the east.
Share with: hikers, joggers, family groups
Restrooms and picnic tables at Anti-Aircraft Peak Trailhead.
Parking for: At Sky Country
Trailhead, 10+ trailers. At Anti-Aircraft Peak Trailhead, 4-5
trailers depending on how people park.
King County Parks has added a downloadable "brochure" (including a map) for this park to their "Backcountry Trails Map Brochure Series." It's pretty detailed.
Cougar Mountain is full of history you can still see, starting with the coal you can see alongside the trails here and there. Coal was discovered in the area around 1860, and before long the mountain was riddled with mine shafts to dig it out. Red Town, for which the trailhead is named, was a company town for mine workers, so named because all its houses were painted red. The nearby Rainbow Town trail refers to another company town where houses were painted any color. Mine shafts ran as deep as 520 feet below sea level, and as shallow as... well, they still cave in from time to time to this day. The Cave Hole trail skirts past many caved-in shafts that date to the later part of the area's mining history, when the big mining companies had moved out for more lucrative locations, and smaller-scale miners were picking over what remained. One of their tactics was to mine out the coal in the roofs and support pillars of the existing tunnels, where they got their nickname of "grassroots miners" - it was said they would mine "up to the grass roots." Needless to say, this caused a lot of collapses, and is a good reason not to go off-trail in the park. In 1987, the Office of Surface Mining reportely identified and sealed 166 different openings. However, new sinkholes still occur on occasion. In addition to cave hole pits, you can also see the sealed entrance to the Ford Slope (mine entrance) and the remnants of ventilation shafts, steam plants, and other mining equipment here and there.
During the Cold War, Cougar Mountain was pressed into service as a Nike Missile site. The meadow by the Sky Country trailhead was where the missiles were, and Anti-Aircraft Peak housed the radar that controlled them. Previously, the mountain had been a lookout site in WWII against Japanese incendiary balloons, equipped with anti-aircraft guns. The missile site was declared obsolete in 1964, and the military began procedures to transfer the area to county ownership not many years later.
Check out this mining history PDF from the WTA.