Starting at San Juan Lookout, the trail starts with a couple miles of easier terrain and eventually crosses San Juan Road.
After crossing San Juan Road you'll stay right at the fork, as left will take you on the Bajada Trail
. This section of National starts climbing and is full of washed-out areas, rocks, and several obstacles on the way up. Once you are out of the canyon, the trail steeply follows the ridgeline with a few short downs and then steep ups. You'll pass several abandoned mines along the way (just a few feet off the trail!) and run along the backside of the mountain for a bit where the trail becomes exposed but is suitably wide and smooth through the exposure.
The next major intersection will be at Ranger Trail, which would take you back down to the 5 Table TH/Ranger Station. If you continue on National, the next section will take you underneath the TV antennas and cross the paved road to the lookouts twice.
National then takes you over Telegraph Pass and up to the Buena Vista Lookout. From the Buena Vista Lookout to the end of National at the east end, it gets rockier with bigger obstacles to navigate. Be careful of mountain bikers as they use this section of the trail frequently.
National will end at a Dirt Road
that you can take down to the Pima Canyon Parking Area.