Data from "The Handbook of Chemistry and Physics, 54th Ed., and the OED.
Davy, the discoverer in 1812, first used Alumium, then settled on Aluminum (from the Latin word alumen, alum). In 1822, it was proposed in the Quart. Rev. that Aluminium be used "in preference to Aluminum, which has a less classical sound." Some writers preferred it because it fit with Sodium, etc. in spelling.
Somehow, classical Latin scholars got into the argument, many of them coming out in favo(u)r of Aluminum. (Don't ask me why, my Latin was taught to me too long ago).

In 1925, The American Chemical Society came out in support of Aluminum. In all American (I should say USA, Canada is bivalent) journals concerned with chemistry, and most American (USA) scientific journals in all fields, the use of Aluminum has been upheld and enforced by editorial boards. Aluminum thus continues to prevail in the USA.
Elsewhere, Aluminium remains preferred.

Now, there is always sulfur vs. sulphur .....!