Any chance you ordered a custom PC? You know, asked for more memory or a bigger hard drive? If so, the factory in China built you a custom model and dropped shipped it.
Even if you didn’t customize your order, why should the company your order it from stock them in a warehouse in the U.S.? Computers go bad very fast. in six months, everything you have in your warehouse will be obsolete, so there isn’t a great need for stocking inventory.
Even if they did stock some in the U.S., they may only ship those for express orders. Someone who must have their computer the very next day. If you don’t mind waiting a week, why not simply get it from China?
I ordered a MacBook Pro a month ago, and it was shipped from China, and I still got it in less than a week.