After the election debacle of 1800, there was major change to the Electoral College in the Constitution.. Thus my research starts with 1804 and the modern version of the Electoral College.
|President Barack Obama|
In 2008, Democrat Barack Obama won his first term against Republican John McCain with 52.87% of the popular vote and won 365 of the 538 electoral vote. His popular vote and electoral vote margin of victory placed 22nd and 23rd respectively on the "closeness" list. So neither even fall in the top half when it comes to margin of victory
In 2012, President Obama won re-election against Republican Mitt Romney with 50.96% of the popular vote and won 332 of the 538 electoral vote. The popular vote spread in that race was 13th closest (out of 48) since 1804 and the electoral college margin was the 17th closest (out of 53). So not only was it not a landslide from either a popular vote or electoral vote standpoint, it was actually an historically close election.
For the record, the closest popular vote margin was the 1880 race featuring Democrat Winfield Scott Hancock and Republican James Garfield, a race Garfield won. The closest electoral college race was in 1876 and involved Democrat Samuel Tilden And Rutherford B. Hayes. That race featured electoral college deal in which Democrats agreed to propel Hayes to the presidency in exchange for the Republicans withdrawing troops which were in the South enforcing Reconstruction following the Civil War.
The biggest landslides? On the popular vote side that would be Republican Warren Harding's victory with 60.32% of the vote in 1920. His opponent, Democrat James P. Cox, only managed 34.15% of the vote. As far as the Electoral College, the biggest landslide was Democrat Franklin Roosevelt's victory over Republican Kansas Governor Alf Landon, The second biggest electoral college landslide was Republican Ronald Reagan's victory over Democrat Vice President Walter Monday. Reagan captured 95.2% of the electoral vote compared to the 97% of that vote garnered by FDR.
Correction: The original article had Obama winning 332 electoral votes in 2008 and 2012. This was a mistake. He won 365 electoral votes in 2008 and 332 in 2012. The rankings were based on the correct 365 total and did not change.