Why did “sceptical” become “skeptical” in the US?

Question

Compare the following two Google Ngram Viewer charts for sceptical vs. skeptical in American English and British English:

British English

American English

My interpretation of these charts is that:

1. Before the 1910-1920's, sceptical was used in both American English and British English more than skeptical.

2. Something happened in the 1910's in American English that made the usage of skeptical become much more common than sceptical. This change never happened in British English.

Why did this change happen in the US? What was its trigger?

Note that while etymoline.com states that the sk- spelling is preferred in the US, it does not explain why it became so more common than the sc- spelling, in particular since the 1910-1920's.

skeptic also sceptic, (...) The sk- spelling is an early 17c. Greek revival and is preferred in U.S.

Answer 1

The reason? A man by the name of Noah Webster, who wrote America's blue-backed spellers, and her first dictionary.

Noah Webster, was an English spelling reformer, and one of the chief advocates of English spelling reformers is that spelling should change alongside pronunciations :

Pronunciations change gradually over time and the alphabetic principle that lies behind English (and every other alphabetically written language) gradually becomes corrupted. If the maintenance of regularity in the orthography of English is desired, then spelling needs to be amended to account for the changes.

This change was made along with many different words (e.g. colour to color, grey to gray, -ise to -ize)
"Sceptical" changed to "skeptical" due to Noah Webster's spelling reforming efforts, basically.

Answer 2

Following Thursagen's trail on Noah Webster, I found the following note in 1828 Webster's entry for skeptic

This word and its derivatives are often written with c instead of k in the first syllable, -- sceptic, sceptical, scepticism, etc. Dr. Johnson, struck with the extraordinary irregularity of giving c its hard sound before e, altered the spelling, and his example has been followed by most of the lexicographers who have succeeded him; yet the prevalent practice among English writers and printers is in favor of the other mode. In the United States this practice is reversed, a large and increasing majority of educated persons preferring the orthography which is most in accordance with etymology and analogy.