As I mentioned earlier, the Mid State Trail is temporarily rerouted on the Jackson Trail. You'll find that most people hiking the Mid State Trail will stick to the Jackson Trail unless they are in need of water. With it's easy access from Jo Hays Vista, most people will use this as a starting point for hiking and will be fully stocked with water.
However, you don't need to be hiking the Mid State Trail to enjoy the Jackson Trail. The trail is an out and back hike unless you incorporate the descent into the valley by following the Mid State Trail proper. However, at this point in time, a circuit hike of this nature is not advisable with the inaccessibility of this section of the Mid State Trail. I would even suggest hiking the Jackson Trail, at least the first mile, as your first hike or even a hike suited for children. Once you get out past the first two vistas, however, the trail is little more challenging with many rock fields to traverse.
The trailhead is clearly marked by a sign, located to the left of a gated mountain road. You will hike back this road for about 0.3 miles back to a number of radio towers. At the last radio tower the trail begins. It's a little rocky, but flat and wide, so hiking in sneakers is possible.
You will continue along this flat, wide part of the trail for about 0.75 miles from the trailhead. At this point you will enter a stand of pines and the trail will turn slightly to the right. This is where you will encounter your first vista; David's Vista. Directly across from David's Vista, on the northern side of the mountain is another vista. If you are looking to do a simple day hike or are hiking with children, take a moment to enjoy this two beautiful vistas, and then head back the way you came to the trailhead. If you are looking for a longer, more challenging day hike, continue on.
I had an agenda for this hike, aside from enjoying the out of doors. At the end of the Jackson Trail is a section that was devastated by a forest fire about 4 years ago. With the lack of trees, this section of the trail gets quickly overgrown with underbrush and saplings. I was also hiking the trail just to get an idea of any blow downs or trees that may have fallen across the trail and needed to be cleared.
I noticed that someone had recently reblazed the trail, so you will have no problem following the trail across the mountain top. Continuing on the hike you will encounter a number of vistas, almost exclusively on the southern side of the mountain. The trail is somewhat challenging in places as you will need to traverse some larger rocks and boulders. Hiking boots are a must for this section of the hike.
Once I reached the area of the trail that had been burnt by the forest fire I began to clear the trail where it was needed. There were many section where you couldn't walk on the trail without needing to push aside limbs and undergrowth. I'm happy to announce that the trail is now a little easier to navigate but this section is going to need constant maintenance for a number of years to come.
If you're looking for an easy day hike, then I definitely recommend hiking out to and enjoying David's Vista. If you want something a little more challenging, then try hiking the entire Jackson Trail. However, if you are looking for a circuit hike you're going to have to wait until the Mid State Trail that descends to the valley below has been cleared and is passable. All in all, the Jackson Trail makes for a nice hike, and located only a few minutes from downtown State College, should make it onto your list of hikes to do in Central PA.

The last section of the Jackson Trail, about a quarter of a mile before it meets up with the Mid State Trail proper. This section was burnt by a forest fire in 2001 and quickly becomes overgrown with brush and saplings.