After more than 13 years together, Little Big Town finally received the keys to country music's penthouse. The quartet has its very first No. 1 hit with "Pontoon," the fun-loving song that has already sold a million copies and is LBT's fastest-rising radio single to date.

Written by Barry Dean, Natalie Hemby and Luke Laird, "Pontoon" is, no doubt, one of the biggest songs of the summer. It has started Twitter trends and even a fashion craze, as fans and fellow celebrities are sporting T-shirts emblazoned with a phrase from the song, "Mmm....motorboatin'."

"This single has been so much fun," says Little Big Town's Phillip Sweet. "I don't think we've ever seen a reaction like this to a song we've had out."

"Well, we've never had a song with motorboatin' in it before," bandmate Kimberly Schlapman adds with a laugh. "Maybe that's what we've been missing this whole time!"

The news of LBT's first chart-topper comes exactly one week before their new album, Tornado hits stores (Sept. 11). "Pontoon" is the project's first radio single.

"After working towards this for 13 years, it's an even sweeter reward than we dreamed!" says Kimberly of their long-awaited chart feat. "We're just soaking it all in and it feels so good!"

"We'll be celebrating this for a while," adds LBT's Karen Fairchild. "We can't say thank you enough to country radio, the fans and our whole team for giving us our first number one!"