Is it riffing off ranch dressing? I've heard that ranch is associated with the US, outside of the US.
Edit: looks like "american sauce" can refer to a multitude of things. Typically it seems to either be some kind of ranch or thousand island.[1] Both of which are separate from "Sauce Americaine", from French cuisine.[2]
2nd edit: If the OP is talking specifically about Heinz brand "American Sauce", apparently the closest match in American cuisine is either thousand island or big mac sauce/"secret sauce" used on burgers (which is based on thousand island). It is pretty American, come to think of it.
[1] https://www.thedailymeal.com/news/travel/which-mayonnaise-he...