PHOENIX — Three years ago, Kate Rogers was caught in the Bay Area struggle. She paid the astronomical rents. She did the crushing commute. She lived the frustration of always thinking about money even though she was a well-paid professional in the booming technology industry.

And then, just like that, the stress went away. All she had to do was move to Arizona.

“I didn’t want to have to decide between picking my son up at school and being successful at my job,” said Ms. Rogers, who runs the Phoenix-area offices of Weebly, a San Francisco company whose software makes it easier for regular people to build websites. “In San Francisco, that would not have been possible.”

As start-ups across San Francisco and the Silicon Valley try to contend with high salaries and housing costs, many are expanding to lower-cost cities in the West and employing more people like Ms. Rogers. For Phoenix, which is about a 90-minute flight from San Francisco, the Bay Area’s loss is its gain.