Elon Musk had long been drifting away from the political culture of California, railing against its regulations and pandemic-era lockdowns. So, four years ago, he decided to move to Texas, eager to embrace its wide-open business culture and be embraced by its Republican leaders.

Since then, Mr. Musk and his companies have spread across Texas with accelerating speed, transforming ranches into factories outside of Austin, using coastal lands as a launch site for space travel near Brownsville and turning farms outside Corpus Christi into what will soon be the state’s first lithium refinery, for his electric cars.

The headquarters of X is moving to Texas. Mr. Musk's largest factory for Tesla vehicles arrived in 2022, north of Austin. His tunneling company, the Boring Company, has its own small bedroom community of mobile homes and is testing its technology with a pair of tunnels under a farm road outside the city of Bastrop.

Mr. Musk has done more than simply move businesses from a blue state to a red state. His growing presence in Texas has been part of a high-profile political transformation — from a Democratic electric car evangelist to perhaps the most significant backer of President-elect Donald J. Trump — that could help further expand his businesses in the state.

During the presidential campaign, Mr. Musk funded almost entirely on his own a ground-game effort to elect Mr. Trump that cost more than $175 million. Since the election, Mr. Musk, a major federal government contractor, has been a prominent adviser to Mr. Trump on cabinet selections, and was himself selected to help lead efforts to reduce federal regulations and spending.