This route isn't heavily trafficked by runners but you are more likely to encounter mountain bikers or horses.
The 50-Year Trail starts in Catalina State Park at the Equestrian Center where you can park, although you'll need to pay for entry into the park (currently $7 unless you have an Annual Pass). The trail begins on the northeast side of the Equestrian Center and is signed. Follow the dirt path out to the east and then make a left up the hill, again following the signage as a right will take you down the Bridle Trail
. The first 1.5 miles or so is predominantly uphill and moderately rocky. It begins to flatten out after awhile and becomes a bit less technical.
At around 2.5 miles into the trail, you'll come to a gate which signifies the border of Catalina State Park, Be sure to close the gate behind you to keep cattle from getting in the park. At this point the signage for the 50-Year Trail indicates continuing straight down the doubletrack path, but there is a singletrack path that's MUCH more enjoyable if you take an immediate right. This path does have some markers periodically but is pretty easy to follow anyway. You'll cross the Link Trail that leads back to the Sutherland Trail
in Catalina State Park. Eventually you'll descend into a valley and cross a couple of dirt roads before climbing back up towards the parking lot off Golder Ranch. Right at 5 miles in, you'll come to a fork in the path and you can head to the left up towards the parking lot or if you're continuing on the 50-Year Trail further north you can stay straight on the path.
Overall this is a pretty good route with some moderate climbing, semi-technical sections of trail, and decent views throughout.