DALLAS, Texas - Collin County's explosive growth is impossible to miss - and Dallas Mayor Eric Johnson isn't mincing words about what it means for his city.

"I hope everybody who's been watching the news this week understands that I wasn't crying wolf," Johnson told Dallas City Council Wednesday.

"The wolf is not in this room, the wolf is up the tollway." The warning came as two of Dallas's professional sports teams - the Stars and the Mavericks - announced plans to relocate, joining a wave of big businesses already heading north.