In the late 1800s, a spelling-reform movement was led by Noah Webster. This was the beginning of an attempt to introduce more "phonetic" spelling into American English. The movement continued through the first half of the 20th century.
Noah Webster and his successors were able to introduce a number of uniquely American spellings to varying degrees of success.
Some changes stuck, such as "color" and "neighbor".
Others didn't. We still use "engine" instead of "engin"; and "rough" instead of "ruf."