The Associated Press will count the nation’s vote in real time Tuesday and report the results of presidential, congressional and state elections — as it has for more than 170 years.

The way the information is compiled on election night may have changed — cellphones as opposed to landlines, electronic data feeds as opposed to “election tabulators” fitted with rolls of paper, journalists crowding around computer screens, as opposed to teletype machines.

But the AP's role in getting accurate results out to the nation and the world remains the same.

“There is no national election commission in the United States that tells us who won on Election Day,” said David Scott, a deputy managing editor who helps oversee AP’s coverage of elections. “Statewide results aren’t available in every state, either. If we want to know who the next president will be, we’ve got to do the math ourselves — county by county nationwide.”