re: What would you say is the national dish of the USA?

The idea of Turkey on a holiday is certainly American. The tradition in England was a Goose. I've never had goose so don't know if it tastes similar.

However, for the first 100 years of the US the holiday turkey was shot in the wild. Tastes different and must be cooked differently than the white farm raised turkeys developed during the industrial revolution.

Wieners are not American but the idea of putting them on a long bun was invented in the US.