More than 84,000 people jammed Invesco Field at Mile High to witness Barack Obama's acceptance of his historic Democratic presidential nomination Thursday night. The estimate was based on the number of credentials scanned by security officers as delegates, volunteers, fans, voters, and news media paraded into the downtown football stadium hours before Obama accepted the Democratic Party's presidential nomination, said Nancy Kuhn, a spokeswoman with Denver's public works department. The Denver Broncos' home stadium normally holds 76,125 people, but more seats were placed on the field for the event, said Kuhn, acting as a spokeswoman for a multi-agency information center set up for the Democratic National Convention. The seats on the field were reserved for delegates and special guests. The media was staged under several tents and on elevated platforms on the field, just in front of the stadium seats. Hours before the Secret Service opened the gates, people in shorts, flip-flops, sneakers and sandals lined up two- and three-abreast in a queue that snaked for a mile, threading under nearby Interstate 25 and along railroad tracks usually clogged with trains hauling coal out of the Rocky Mountains. "I'm ecstatic to be here," said grocery worker Susan Murphy of Denver, who got her Obama speech credential from the United Food and Commercial Workers Union.At one point the line to get in was so long and so contorted that it was difficult to tell where the line began and ended, and which way the line was moving. A five-mile stretch of Interstate 25, which runs past the stadium, was closed for security reasons. Some 11,000 vehicles use that stretch per hour during a typical weekday rush, the Colorado Department of Transportation said. Traffic disruptions were minimal."Everybody got the message. Everybody was gone," said department spokesman Michael Murray. Vendors sold Obama T-shirts, posters and even Obama foam fingers, the type usually seen at football games. Most celebrants wore Obama gear and had their Obama campaign "community credentials" hanging from their necks -- coveted tickets obtained through Internet registration or through their work as volunteers for the Obama campaign.One man walked quickly through the line, asking if anyone had an extra ticket. He said he was willing to pay $100 for a ticket, but no one was willing to give up their chance to see history in the making. Inside one security checkpoint, a drum line from Denver's East High School played and led the crowd in cheers of "Obama!" They wore red Democratic National Convention T-shirts. John Vialpando of Arvada, Colo., a Republican and a hedge fund trader, scored a credential, as did his brother, Tim. "This is history. I don't care if you're Republican or a Democrat," said John Vialpondo, 27. Tim Vialpando, 28, is a Democrat and a teacher who wore a National Education Association T-shirt to the event. "I think there's a glimmer of hope that he'll see the light tonight," Tim said of his brother. "He was very impressed by the Clinton speeches." Throngs lined up hours before the nighttime speech. With the threat of dehydration ever-present in the sun and Denver's mile-high high altitude, city officials used a fire hydrant to replenish a truck dispensing water to the thirsty crowd. Coke handed out free bottled water and gave samples of their other non-carbonated drinks. There were at least two checkpoints at the tightly controlled venue: One to get onto the stadium grounds, and another to get to the blue-and-orange seating of the stadium itself. Transportation Security Administration workers staffed a tent where people passed through more than a dozen metal detectors. Once inside, many took pictures of a panorama that included the signature bucking Bronco atop the stadium and the Denver skyline. Dozens of people who showed up hoping there would be a public viewing area outside the stadium huddled around a small radio to hear Obama's speech. A parking lot at one end of the stadium complex set aside for protests was empty. Joni and Nick Fisher of Platteville, Colo., were thrilled when they got their tickets: Row 6, Section 123, right at the 50-yard line for a Broncos game -- and perfect for viewing Obama's center-stage speech. But when they got there, they found their seats were behind the field stage where Obama was speaking. They stared at a black curtain and rigging holding up lights and cameras. "Surprise! We'll get to see him on the Jumbotron," Joni Fisher said. "It's OK. We're here. It's history."