Pennsylvania is probably the single most important state in the presidential race this year, and because election workers aren’t allowed to start processing mail ballots until Tuesday morning, it will probably take a few days to report all of its results. Adding to the potential chaos, counties aren’t actually required to count mail ballots on Tuesday — just strongly encouraged to do so.

That’s why this map from the Pennsylvania Capital-Star is so useful:

It shows when each county plans to start counting mail-in ballots, how well equipped they are to count quickly and how many they have to get through before they’re done. This is also important because the counties that don’t plan to start counting mail-in votes until Wednesday will almost certainly have too-good-to-be-true results for Trump on Nov. 3.