* No central, continuously updated database: There's no agency tracking every vehicle's origin and current operational status. Registration data is collected at the state level, and it doesn't always distinguish between domestic and foreign manufacturing in a consistent way.
* Definition of "US-made": What constitutes a "US-made" car is complex. A car might have parts sourced globally but assembled in the US. The percentage of US-made content varies widely between models and years.
* Vehicle lifespan and scrapping: Cars are constantly being scrapped, exported, and taken out of service, making any count a snapshot in time.
While various research firms and government agencies collect data on vehicle production and registrations, they don't provide a precise number of currently operating US-made cars. Any estimate would have a substantial margin of error.
