Fans swamped Ticketmaster to snap up seats for the string of shows, which start with the previously announced 7:30 p.m. Sept. 4 concert.
The Rosemont venue seats about 18,500, but Brooks has made quick work of sales there before. In 1997, he sold out eight shows at the venue -- then called the Rosemont Horizon -- in a day. He broke Genesis' 1987 record by selling 139,000 tickets in less than four hours.
The world tour is the first in 13 years for Brooks, and his first shows in the Chicago area since '97. He is touring with his wife and fellow country artist Trisha Yearwood.
Tickets for what was supposed to be a single show on Thursday, Sept. 4, were set for sale at 10 a.m. Before fans could scramble to get them, however, three more shows were added.
By noon, Ticketmaster was selling tickets for five shows and Brooks himself took to US 99.5 Chicago to encourage fans to stay in the queue if they were waiting. And the numbers kept growing throughout the morning.
"They're telling me that the system is just getting crushed right now," Brooks said to the radio station's Lisa Dent and Ramblin' Ray Stevens. "I wasn't expecting this."
Brooks said 160,000 people were waiting for tickets online, and he begged people not to go away.
"We'll get it done," Brooks said.
Then, Stevens said the number was actually 300,000.
Brooks called the station again at 12:40 p.m. with an announcement.
"We are adding a ninth and tenth show," he said. "And we are gonna call it at that."
Fans took to Twitter using #GarthBrooks to express their excitement about the show. Some fans said that they waited up to four hours to secure a ticket for the world tour's first stop.
Seana McPherson of Mount Prospect was ready at 10 a.m. as soon as the tickets went on sale and waited an hour before she bought four for the Sept. 5 show. By the time she got through, Thursday's show was already sold out.
"I last saw him in college and knew that if he booked a concert, he would typically add another one," McPherson said. "No way was I expecting 10."
McPherson remembered in college sending a check in the mail to buy a ticket for a Brooks concert. She said that tickets for his shows are priced the same, whether the seat is in the front row or the nosebleed section. That's true of the Rosemont shows as well, where tickets are $65.50.
"It used to be a lottery. If you didn't get one, they sent your check back," McPherson said. "He didn't want anyone to have an unfair advantage."
The tour is seen as a comeback of sorts for Brooks, who retired in 2001 to spend time with his family, though he has done some shows since. The Recording Industry Association of America lists Brooks as the third top-selling artist in terms of albums, behind The Beatles and Elvis Presley.
Brooks' Rosemont shows -- some scheduled two a night -- are on Thursday, Sept. 4; Friday, Sept. 5; Saturday, Sept. 6; Thursday, Sept. 11; Friday and Saturday, Sept. 12 and 13; and Sunday, Sept. 14.