Vermont was once an independent state (that was the first VT republic); so was Hawaii (not a republic). If the US ever crumbles these 2 flaky edges will be the first to fall off.
Between the overthrow of the monarchy and annexation by the US, Hawaii was a republic.
People always act like this is so unique to their state. But it's common. First off all 13 colonies were independent states before and after the Revolution. It took several years to write and ratify the Constitution, which is where we were really joined. Texas was independent as well as part of Mexico, Spain and France before joining up. ("Six Flags"), California was the Bear Republic. I'm sure there were others. Some areas went diretly from European control to American: the Louisiana purchase and Alaska come to mind.