The US engines started in NY state but after the company was bought they were built right here in PA !
They were built as a clone to the Quadra engines so a US 41 is very similar to a Quadra 42. I have both US and Quadras and they are engines that start easily and run for ever. A bit heavy compared to today's chicom engines but perfect for scale planes and warbirds. They made 32,35,41,42,57cc engines. Most magneto but a few electronic.
Here was their latest website: http://www.usqaero.com/index.html

Some more history on the company who bought US engines