A.J. Frank watched the Phoenix real estate market and its entire economy implode as he was graduating from high school in 2009, a scarring experience that has made him a cautious saver. He is again living through a major economic upheaval as the cost of living climbs sharply.

Phoenix — among the hardest-hit cities during the housing crisis — is now on the leading edge of another painful economic trend as the United States faces the most rapid inflation in 40 years. The city is experiencing some of the fastest price increases in the nation, something Frank has felt firsthand.

His landlord tried to raise his rent nearly 30% this year, prompting him to move. Frank, a 31-year-old engineer, is still paying $250 a month more than he was previously, and rising grocery and gas bills have reduced his disposable income.

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“It’s always traditionally been a pretty affordable city to live in, but it’s getting more expensive,” Frank said of Phoenix.

While inflation has been rising quickly across the country, it is especially intense in Sun Belt cities such as Phoenix, Atlanta and Miami, which have experienced price increases well above 10% this year, much higher than the national rate of 8.5% in July. Prices in the Southern United States have risen 9.4% over the past year, the fastest pace of any large region in the nation and more rapid than in the Northeast, where prices are up 7.3%.

Part of the divide can be traced to fuel and electricity costs, which surged earlier this year. Because many Sun Belt cities depend on cars and air-conditioning, those purchases make up a larger percentage of consumer budgets in the region. And, just as it did in 2008, housing is playing a crucial role — this time, through the rental market, which is a major contributor to overall inflation. In Phoenix, rents are up 21% from a year ago, and in Miami, they are up about 14%. For urban dwellers nationally, rent is up only about half as much, 6.3%.