a. In the 1856 election there were 4.05 million votes cast.
b. In the 1860 election there were 4.6 million votes cast
c. In the 1864 election there were 4.03 million votes cast- 11 states did not vote
d. In the 1868 election there were 5.7 million votes cast- Texas, Mississippi and Virginia did not vote. Ex-slaves voted.
e. In the 1872 election there were 6.4 mllion votes cast
All the elections except for item c. make sense.