The pattern. For decades up to the 1992 election, presidential race was almost always a landslide. Example, 1988 election, it was 426 delegates to 111. 1992 established the "red state"/"blue state" trend. Many states that voted Democrat in that election have never voted Republican again. Many states that voted Republican in that election have never voted Democrat again.
The states that did manage to change since then are "swing states." Delegates to the victor is usually ~300 instead of ~400 like it was prior to 1992.