Yes, American. The Yardbirds were fairly big here. Maybe a little less popular than the Kinks, definitely less well-heard than the Beatles and Stones. Their hit singles were on broadcast radio (AM at that time). Their biggest hits were"For Your Love" and "Heart Full of Soul" from the Clapton era. (I don't remember hearing these on radio, but they charted well in the States. From the Beck / Page era: "Shapes of Things"; "Over Under Sideways Down"; "Happenings Ten Years Time Ago"; and "Little Games"; "Ha Ha Said the Clown"; and "Ten Little Indians" (the last 3 are not nearly as good as the first 3 with Beck / Page , imo). Clapton was the best known (for Cream) during the period; Beck was less popular solo and in other groups. Jimmy Page--well, you know that story. I owned Shapes, Over Under, Happenings, and Little Games as 45's (alas, all my early vinyl is gone).

Here's a discography with data for British and American albums and singles. https://en.wikipedia.org/wiki/The_Yardbirds_discography