In the 1960 election, there were 32 states where the margin of victory was within 9%. In recent elections, that number has dropped by half or more:

In addition, the margins of victory have gotten wider in most states, leading to the vast majority of Americans—from big and small states, at all points on the political spectrum—being ignored in presidential politics:

Fortunately, there is a solution.  If enough states agree to give their electoral college votes to the winner of the national popular vote, then presidential candidates will have to compete nationwide, not just in the small number of states that are likely to be close.