In other words: Which state will have the closest race.

This market will resolve YES to the state with the lowest margin between top 2 candidates for President, and NO to all the other states.

The lowest margin will be decided percentagewise.

Example:
State A voted 49.7% for party X and 50.3% for party Y. The margin is 0.6%

State B voted 50.5% for party X and 49.5% for party Y. The margin is 1%

State A resolves YES and State B resolves No, regardless of the absolute vote count.