The small states wouldn't stop bitching about being underrepresented in the House, claiming population wasn't really important. Meanwhile, the larger states were getting sick of a voter in Alaska having three times the electoral vote of one in California, due to the butt-ugly electoral college system.
Both agreed to Rule 14: states with 15 or more electoral votes would become independent of those with 13 or less (there are none with exactly 14).
Sadly, us Massholes are now stuck with the redneck states. RCP counts the states badly, somehow they shortchanged us 6 votes on this one.
270toWin has a better map anyway, the interface is much easier:
http://www.270towin.com/
NOTE: you'll have to take a screenie and save as PNG. It's a bit of a pain.