Republicans:
1856 - Vermont (78.0% Fremont)
1860 - Vermont (75.9% Lincoln)
1868 - Vermont (78.6% Grant)
1872 - Vermont (78.3% Grant)
1876 - Vermont (68.3% Hayes)
1880 - Vermont (69.8% Garfield)
1884 - Vermont (66.5% Blaine)
1888 - Vermont (69.0% Harrison)
1892 - Vermont (68.1% Harrison)
1896 - Vermont (80.1% McKinley)
1900 - Vermont (75.7% McKinley)
1904 - Vermont (78.0% Roosevelt)
1908 - Vermont (75.1% Taft)
1916 - Vermont (62.4% Hughes)
1924 - Vermont (78.2% Coolidge) - Home state
1932 - Vermont (57.7% Hoover)
1936 - Vermont (56.4% Landon)
1948 - Vermont (61.5% Dewey)
1952 - Vermont (71.5% Eisenhower)
1956 - Vermont (72.2% Eisenhower)
LOL.
Yep, that was a very, very different state than the one we see today.
Or the GOP is just a very, very different party.
It's a little bit of both, but it's very overrated how much the parties have changed. Vermont's percentages have basically flipped from the '50s. Surely you wouldn't argue that the parties have even kind of switched since the '50s. Vermont experienced a massive influx of hippies during the counterculture days and a large influx of people from MA, NY, CT, etc. in the '70s and '80s. It's not like VT stopped being Republican as soon as the very modern GOP developed. It voted for Reagan twice and the elder Bush once. It even came comparably close with Bush/Gore in 2000.
I highly reject the simply ridiculous notion that VT has always been liberal and it supported the GOP back when the GOP was liberal (which it really never even kind of has been, even if that makes Democrats who now love Abraham Lincoln uncomfortable).
