The answer is the South to vote Republican.
While Colorado has shown a tendency to lean Democratic in recent elections, particularly in presidential elections, it is not the most obvious sign of party realignment. Colorado's political landscape has been more of a battleground state, with shifts occurring over time.
The West Coast, including states like California, Oregon, and Washington, has consistently voted Democratic in recent decades. However, this trend has been more stable and less indicative of a dramatic realignment compared to other regions.
The Plains states, such as Kansas, Nebraska, and the Dakotas, have traditionally leaned Republican. This trend has been consistent over a longer period and does not represent a significant recent realignment.
The Midwest has been a mixed region with states like Illinois leaning Democratic, while others like Ohio and Iowa have been more competitive. This region does not show a clear, consistent realignment towards the Democratic Party.
The most significant and obvious sign of party realignment in recent decades has been the shift of the Southern states from predominantly Democratic to predominantly Republican. This change began in the mid-20th century and solidified in the latter part of the century, particularly with the rise of the conservative movement and the Republican Party's Southern Strategy. This realignment has had a profound impact on national politics.