Little Big Town's 'Pontoon' may have just come off the top of the country singles chart, but the group wasted no time diving into celebration mode. Last Friday evening (Sept. 21) -- the last official day of summer -- Kimberly Schlapman, Karen Fairchild, Phillip Sweet and Jimi Westbrook gathered with friends, family and industry peers atop BMI's rooftop for a big blowout celebrating their very first trip to the top of the charts.

Guests were welcomed at the BMI entrance with a large Pontoon that was parked in the loading zone, blasting music. While they made their way into the party, Little Big Town met with the press to discuss the purpose for the gathering, recalling that special moment when they got the news they had finally topped the country singles chart after 13 years of trying.

"We were on the road, and we got text messages at the same time," Schlapman recalls to Taste of Country.

"It was college football Saturday, and it was during the day time while we were out on tour," adds Sweet. "All of a sudden, we all got the text, and I immediately got off the bus looking for Jimi."

"I think [the girls] had gone out shopping that day," Westbrook notes. "[Phillip and I] were hanging back watching football. Phillip and I ran and hugged each other from across the parking lot [laughs]!"

"We did the whole thing where we found each other and saw each other from across the parking lot... 'Woohoo!'" Sweet says while grinning. "We raised our arms up high like we scored a touchdown [laughs]. It's like we were kids again."

When the girls returned, the celebration was in full swing. "We got some bottles of champagne," Fairchild told us, smiling. "[We wanted to celebrate with] our whole band, crew, tour manager, and everybody. They bring that song to life every night in front of the crowd, so they're such a crucial part of this moment for us. We all had a little champagne toast... and then we toasted for a few more days."

Adds Sweet, laughing, "We're still toasting."

Once the group wrapped up meeting with the press, they joined the partygoers on the rooftop of the building to bask in their most recent success. A fantastic spread of Mexican food was set up, including both steak and chicken fajita ingredients, chips and queso, and Spanish rice.

Once everyone was situated, the group, as well as 'Pontoon' songwriters Luke Laird, Barry Dean and Natalie Hemby, were brought up to the stage, where they were given countless plaques from some of the industry's most prestigious organizations.

It was certainly an honor well deserved.