The action before the debate:
Audience members begin arriving for the debate:
Latest national polling of the presidential candidates:
Reuters/Ipsos States of the Nation project, releasing its data just a few hours before the first presidential debate, found Democratic nominee Hillary had pulled ahead of Republican nominee Donald Trump in the southeastern state of Florida, 49 percent to 45 percent.
Florida is a traditional battleground state, with 29 Electoral College votes. The Electoral College ultimately selects the president.
The States of the Nation project, based on a weekly online tracking poll of more than 15,000 Americans, estimates state-by-state results that will drive the voting in the Electoral College.
It projected that if the election were held on Monday, Clinton would lead Trump in the Electoral College by 259 to 191, with an 88 percent chance of reaching the 270 needed to win, Reuters reported.
Other polls Monday:
Quinnipiac University national poll declared the race "too close to call," giving Clinton a 1-point edge over Trump, 44 percent to 43 percent.
A Monmouth University poll shows Clinton with 4-percentage point lead over Trump, 46 percent to 42 percent.
CNN/ORC polls show 1-point margins for the candidates in Colorado and Pennsylvania: In Colorado, likely voters favor Trump over Clinton, 42 percent to 41 percent; and in Pennsylvania, likely voters favor Clinton over Trump, 45-44.