It isn't possible, I get the whole "lets support america" thing, but really, it doesn't matter that much. The majority of "high level" computer hardware (silicon devices) comes from Germany, Japan, the United States, or Taiwan, the majority of everything else comes from Taiwan, Thailand, or China, it isn't just cheaper labor practices that create the outsource, its the availability of engineering students, trained technicians, government help (for example AMD relocated primary fabrication from Texas to Germany, because the German government offered tax incentives and a good region for building; and because theres an abundance of engineers and employees).
Polywell and Velocity Micro claim "100% made in america", which is entirely untrue, ECS Group manufactures something like 40% of motherboars worldwide, most of which come straight out of Shenzhen, the majority of hard-drives worldwide see a factory in Shenzhen, Singapore, Malaysia, or Thailand, the majority of LCD monitors see Korean or Chinese foundaries.
Basically, the majority of computer parts come from only 10-15 companies, and are rebadged quite a bit before they ever see the United States market (just like how Acura isn't really a car company, its just a name that Honda throws on cars to upsell them for US consumers).
I'm not trying to rain on patriotism, I'm just trying to speak to the global market, not everything can be had from the US, and in most cases, its not always the best to be had from the US (consider, if you buy an Intel chip you're still supporting an american company, which contributes to the US economy, but this company also operates in other locations, such as Israel, so by helping this company turn a profit, it allows it to continue operations around the world, which help other national economies).
So, I'd just go to what Willy said, get the best system you can based on performance, price, warranty support, etc, you could even build it yourself.