The map below, from NationalPopularVote.com, totals general election campaign events by the nominees of the two major parties in 2016.
This is by no means the most useful measuring stick for how the Electoral College skews the importance of voters toward only those in a few states. A candidate goes to a state in order to obtain local media coverage and to bolster enthusiasm among loyalists. But there's no particular reason for a candidate to go to a critical state every day for a week, even if the state were absolutely critical, like Florida. A much better measurement of a state's electoral importance is advertising spending and a secondary measurement is money spent on the ground building field offices and installing the many mechanisms to drive turn-out. Nevertheless, the map of visits reveals what everyone in presidential politics know: the vast majority of American voters are taken for granted in the presidential election