The U.S. was growing at the same rate or faster as the UK from 1830 to 1930, when the UK had an empire and the U.S. didn’t. Then, in the second half of the 20th century when the U.S. had an empire and the UK didn’t, the growth rates were more or less the same in both places in the long run trend (ignoring the UK’s step change hit from WWII).
The U.S. was growing at the same rate or faster as the UK from 1830 to 1930, when the UK had an empire and the U.S. didn’t. Then, in the second half of the 20th century when the U.S. had an empire and the UK didn’t, the growth rates were more or less the same in both places in the long run trend (ignoring the UK’s step change hit from WWII).