The Great Exodus

Era beginning/end

Beginning of the Fourth Age

The most powerful elves of Middle Earth at the time, as well as major figures of the third age (Bilbo, Gandalf), sail from the Gray Havens away from Middle Earth, towards the Undying Lands in the west. This exodus of power ends the Third Age (TA 3021) and marks the beginning of the Fourth Age (FO 1).   The key difference from LOTR canon is that not all elves in Middle Earth leave: only the most powerful (like Galadriel) and the ones most sick of Middle Earth bullshit (probably Elrond, tbh). Yes, this is an allegory for white flight.