Pacific Crest Trail
Did you know that there is a 2,650- mile trail that winds its way from Mexico to Canada along the ridgelines of the Sierras and Cascades? On the way it passes through most of the great national parks of the west, including Sequoia, King's Canyon, Yosemite, Lassen, Crater Lake, Mt. Rainier and North Cascades, as well as state parks and national forests too numerous to list here.
I have a job and family obligations, but I can tell you if I was young & fit & didn't have anybody counting on me for anything I would take six months or so off and hike it all!
In fact, you don't have to do it all at once. The Southern California, Central California, Northern California, Oregon and Washington sections are each about 500 miles and you could easily do one of them a summer for five years. That might be a nicer way to go.
In fact, I think I will hike it! Maybe in five sections over five years. I have summers off, after all. But I think I'll wait until my children are old enough to accompany me, if they want to.
Here are some web sites about the Pacific Crest Trail:
http://www.fs.fed.us/pct/
http://www.pcta.org/
http://www.pcthiker.com/
Too many miles? The most dramatic part of the whole Pacific Crest Trail
is the approximately 220-mile section called the John
Muir Trail that goes
from Mt. Whitney to Yosemite. You could just hike that.
There are some other trails like this that span the continent, but not all of them are completely finished yet:
Appalachian
Trail (eastern states)
Continental Divide Trail (Rocky Mountains)
Ice Age Trail (Wisconsin)
North Country
Trail (Great Lakes region)
Trans Canada Trail
The California Coastal Trail isn't
finished yet, but when it is it will be 1,200 miles long and run along the
entire California coast from San Diego to
the Oregon border, including the Marin County coast.