Starbucks' Nashville expansion is part of a broader fast-food migration to the Southern US. Bloomberg/Bloomberg via Getty Images

Starbucks and In-N-Out have recently announced plans to build corporate offices in Tennessee.

The moves are part of a broader southern expansion across the fast food industry.

New and legacy brands are expanding in the South due to demand, lower costs, and easier hiring.

Starbucks is planting a corporate flag in Nashville. In-N-Out is building an Eastern hub in nearby Franklin, Tennessee. And across the South, a long list of fast-food names — like Whataburger, Cava, and Jersey Mike's — are expanding.

From Texas to Florida, burgeoning and legacy fast-food companies are clustering their offices and growth bets in the region, chasing lower operating costs, easier hiring, and a customer base that's clamoring for more options.

Recruiters and consultants who work across the restaurant industry say the move has been building for years, but is now accelerating.

"It's the old adage…