JOURNEY? They invented “butt rock” I certainly hope you weren’t serious!
And Steppenwolf is Canadian. They formed in Toronto, all the members are Canadian, though they made it big in L.A. And John Kay was German by birth, but raised in Toronto.
The problem with comparing British influences to American influences is that British bands tend not to “make it” unless they “make it” in America, while the converse is rarely true (Only three major American acts I can think of were bigger in Britain before America: James Taylor, Jimi Hendrix, and The Pretenders, though the last two had primarily British bands).
Bob Dylan is easily one of the top (if not #1) musical influence of all time, first as a songwriter, then with the release of Highway 61 Revisited as a performer in his own right.
Buddy Holly is often underrated by listeners who are used to overproduced, digitally enhanced music. He was the Beatle’s #1 influence (John Lennon picked the name “the Silver Beetles” as an homage to Buddy’s first band “The Crickets”) Buddy Holly was the first major performer of “garage rock.” His early singles were known for their simple arangements and easy chord progressions. The Crickets were the first real three-piece (guitar, drum, bass) at a time (the 1950’s) when most of rock and roll was heavily influenced by big-band style instrumentation. 90% of rock bands since The Crickets have used the same basic instrumental formula, though few did before him.
The Allman Brothers Band is important for fusing the “Southern Rock” sound with Jazz. Duane Allman (who Clapton admitted to being a better guitarist than himself, and to whom Clapton played second banana to in Derek and the Dominos) had far reaching influences as a studio musician appearing on many of the early R&B recordings at Muscle Shoals studio in Alabama.
Booker T. and the M.G.'s likewise were a HUGE influence due to their insturmental prowess. They were THE house band at Sun records in Nashville, and also were a huge influence on R&B music. Its unfortunate that they are most remembered as “The Blues Brothers Band” since their influence is far greater than that.
Nirvana, whether you personally like grunge or not, WAS a huge influence in all of the music in the english speaking world. Bush (UK) and Silverchair (Australia) only show how the basic Nirvana formula had a HUGE influence in all rock music.
There you go, five from the U.S. side. If you ask me tomorrow, I might come up with a different 5. If your looking for the 5 biggest selling artists, well, that has little correlation to musical influence, but that is a different question altogether.