BOISE, Idaho — The tech company office where Mikelle Oliver works as a recruiter opened two and a half years ago and is now so crammed she must share a desk.

Ms. Oliver and her 200 co-workers will soon move to another building and be joined by 300 more employees. A housing development of 3,000 homes on Boise’s edge, planned for a 20-year build-out, is about a decade ahead of schedule. On the city’s hippest strip, young people pack the outdoor cafes on a late spring weeknight.

These are heady times for Idaho’s biggest metro area, with an influx of newcomers, a spike in home prices and a jolt of high-wage jobs in professions like payroll services and accounting that have made Idaho the fastest-growing state in the nation. Boise has driven the growth — more than four in 10 Idaho residents now live within a half-hour’s drive of the State Capitol in the heart of the city.

With that wave of urbanization and economic development has come a new political chemistry in this conservative rural state. Idaho’s new residents, clustering in Boise’s boom zone, are creating uncertainty about how they might vote in Tuesday’s primary for governor in a moment when economics, politics and demographics are all in motion.