That depends on what OP really means. "Made in the USA" and "assembled in the USA" are two different things, I really doubt Sundown (or any other car audio manufacture for that matter) are truly "made in the USA." For example, are the cast baskets and magnets made with raw materials mined from an US-based mine and cast/pressed in a US-based shop? Are the raw minerals and oil for making rubber/foam/woven spiders from US soil? How about the nickel-plated terminal posts, are they machined by a guy in the US? Ask Sundown, ask DC Audio, ask whatever else is around, ask them, where are the minerals mined from and who did the mining, and they'll say they have no idea. Is that bad? No, not really, car audio is nowhere near as important as an airplane chassis or a ship's hull or a car tire where the purity of the material used can affect people's lives, car audio can completely disappear tomorrow and it wouldn't have nearly as much impact as say, Dow and Nasdaq both drop 2000 points.
What people want is quality control done by people who care, if a design/part is defective and/or questionable on longevity then it should be caught by the QC guys, which people tend to trust when they're in the US. However, the fact that many car audio brands (especially the internet brands) use foam or crappy hard rubber surrounds tells me that their products all have a short finite life. Currently, there are NO car audio brands that are "made in the USA", they're assembled in the USA using sourced parts, which I want to say is almost as good, but to say they're 100% made in the US is a lie.