Unfortunately for those looking to buy American made products, Mountainsmith moved their production to Taiwan or Vietnam in 1999.
According to people who follow this stuff much closer than I ever would, some of the best stitching and materials production in the world occurs in that part of the world. Manufacturers have found that, after working through the initial kinks, moving production to that part of the world actually improves quality control.
Those kinks, however, can take some time to work out. A friend bought a Mountainsmith pack shortly after the move to Taiwan. The pack blew seams in two places in the first month. When he called Mountainsmith to discuss the problem, they told him flatout that production had suffered since moving oversees. They also asked him to wait a couple months until they worked out the problems, at which time they'd send a new pack. 45 days later, he got a new pack that has been bomb proof ever since.