http://www.dailymile.com/routes/1786042-running-route-in-us

around the mt.  Ecco Mt. three miles of trails at the top.

RaiderGwen - do you have more pictures.  That looks incredible!

North Dakota- The Maah Daah Hey Trail. It's a 150 mile single-track mountain bike trail open to hikers, runners, walkers, horseback riders, and bikers. It's point-to-point through the North Dakota Badlands

California - Monterey/Carmel Area.   Fort Ord National Monument is my favorite, though it is becoming more popular (crowded) since it became a national monument.   Garland Ranch Regional Park has two separate peaks, both with 2000' of elevation.   Toro Park is smaller, but has significant climbs and splendid views.     And most frequently.... I run from home through the Del Monte Forest in Pebble Beach.  Over 20 miles of trails with occasional fantastic ocean views and jaunts next to fancy golf courses.

Humboldt County, California -

Arcata Community Forest - Partially situated behind Humboldt State University.  There is nothing flat about The Forest.  Plans are in motion to expand it.  No opportunity to refill water supplies, so be sure to take what you need.

Headwaters Forest Reserve - 11.5 mile round-trip.  1st mile is paved/ADD compliant, next 2 miles are well-groomed, undulating trails.  Then there's a 2-mile climb to the top where you will find an incredible stand of old growth redwood.  A half-mile loop takes you through a portion of the stand, then you can have a blast flying back down the 2 miles, then 3 miles out.  No opportunity to refill water supplies, so be sure to take what you need.

Prairie Creek Redwoods State Park - One of my absolute favorite places.  Run the approximately 5-mile James Irvine Trail to stunning Fern Canyon.  Along the way, you may find yourself face-to-face with an Roosevelt Elk, or venture further out to the parking area and dirt road beyond and you may find a herd of elk lounging and relaxing.  There are approximately 5-6 trail options to connect and wind your way around.  No opportunity refill water supplies unless you go back to park headquarters, so plan appropriately.  NOTE - You can access the trails from the Fern Canyon side, but there is a $5 entrance fee.  If you go to the park headquarters at Prairie Creek, there's camping and no charge for day use.

More for the NY(western) section:

There are some wonderful, pristine upland forest sections along the 500+ mile Finger Lakes Trail. There are also sketchy and road sections and a fair amount of hunting closures. I'll add to recommended sections as I have good gpx tracking for them, but here's the main site with all of the details.

Then there's a wonderful section I run every year when I'm down in Allegany State Park (best described as foothills to the Allegheny Mountains, and don't question the spelling!). Most of this is FLT, but it stays in the park as a point to point route. I will now digress, as while in the park you may want to take advantage of the most fun trail it has to offer, Beehunter. Best of all, no MTB allowed, Nyah nyah.

Back on the FLT, Conservation branch, an excellent section goes through Ellicottville, boasting both the occasionally stunning view and ridiculous hill climbing. I'm told that south of this there's another great section that slowly climbs through cushy pine forest, and I know that north of it there's some of the best singletrack I've ever run on in the McCarty Hill State Forest, but I don't have good data for it atm.

A bit further north of this is another section I run often, really nice, part road through here but I mention it because it crosses rte 20A close to my house. If you head north along the FLT from here, follow 20A east at the crossing up to the first drive past the diner and I'll show you around town.

I'll come out of lurkdom and post a few of my favorite places.  I'm in western NJ near the Lehigh Valley.

 

PA

 

Jacobsburg State Park - Nice mix of terrain.  Popular with horse back riders so you'll need to dodge some horse poop.

 

Lehigh Gap Nature Center - Former superfund site.  The AT runs through there as does the D & L Trail.

 

D & L Trail - Flat canal towpath and rail trails.  Stretches over 100 miles through Eastern PA.  If you're looking for an easy run without dealing with vehicular traffic this is a good option.

 

NJ

 

Merrill Creek Reservoir - This is my go to spot as it's only 5 minutes from home.  Mix of single track and fire roads.

 

Thanks, MrFinn - updated the main list.  Stop by and see us sometime, most of us don's bite.