From the maps, when was the last time the total
number of electoral votes
changed? What caused
this?

In 1860,Abraham Lincoln was elected as U.S. president but his election was accepted by many southern states who decided to secede from the U.S. and form the Confederate States Of America with 6 other states(and eventually 11 all together)

cause-Lincoln had only won the election with 40% of the popular vote,which meant that the majority of the country did not support his ideals-especially anti-slavery sentiment.