Virtually all of the general-election campaign events (119 of 122) during the first 8 weeks of the 2020 campaign have been in just 12 closely divided battleground states.
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Why are Colorado and Oklahoma ignored by candidates, while Nevada (with fewer people and electoral votes) receives 8 of the entire country's 122 visits?
The reason why voters in so few states are getting so much attention is that most states award their electoral votes to the candidate who gets the most popular votes inside each separate state.
Because of these so-called "winner-take-all" laws, candidates only pay attention to voters if they live in a state where the presidential race is very close (that is, within a few percentage points).
Meanwhile, almost all of TV ad spending up to mid-October ($884,000,000 of $1,015,000,000) was in just 6 states, and virtually all was in 12 states.
NPR story