At first glance, the rusted metal pens in the central California town of Patterson look like an open-air prison block. But for Devani Riggs, “the cages”, abandoned since the days they were used to store the bounty of the self-proclaimed apricot capital of the world, play a very different role.

“This one was mine. That one was Patty and Pete,” said Riggs, a 3o-year-old homeless woman, adding that dozens of people had slept in the cramped enclosures.

California’s Central Valley is best known for supplying nearly 25% of the country’s food, including 40% of the fruit and nuts consumed each year. Yet today, backcountry places such as Patterson, population 22,000, are experiencing an increase in homelessness that can be traced, in part, to an unlikely sounding source: Silicon Valley.

The million-dollar home prices about 85 miles west, in San Francisco and San Jose, have pushed aspiring homeowners to look inland. Patterson’s population has doubled since the 2000 census. Average monthly rents have climbed from about $900 in 2014 to nearly $1,600 in recent months, according to the apartment database Rent Jungle, compounding the hardships of the foreclosure crisis, the shuttering of several local agricultural businesses and surging substance abuse rates.

“The rents in Patterson are crazy,” said Romelia Wiley, program manager of the local not-for-profit organization Community Housing & Shelter Services. “Why? I-5.”

The freeway offers commuters access to high-paying job centers near the coast, and the number of people commuting to the Bay Area from the portion of the Central Valley that includes Patterson more than doubled between 1990 and 2013, to about 65,000 people, or at least 15% of the local workforce, according to an analysis by the University of the Pacific.

One fast-growing city, Turlock, began running buses with free wifi to Bay Area train stations last August. Development advocates such as San Francisco’s Bay Area Council are promoting proposals to expand rail service between the Central and Silicon valleys, including a planned high-speed line. Ultimately, the group predicts a “northern California megaregion” fueled by growth in tech jobs, with the Central Valley offering ample land for bedroom communities.

“The families who live here just can’t compete with the commuters,” said Michele Gonzales, deputy director of a local housing authority.

Back in 1908, the Patterson Ranch Company set out to build its namesake city as a small-scale, rural version of Paris or Washington, with boulevards radiating out from a circular town center. Their blueprint lives on today in a tiny downtown dotted with auto shops and a few casual restaurants, the houses gradually getting bigger toward the almond groves on the edge of town.

A hulking new Amazon fulfillment center has opened just off the Patterson exit on the freeway, but otherwise, good-paying local jobs are hard to come by. One monument to past prosperity is the concrete slab on which the Pacific California tomato cannery stood until 2009. Today it is littered with shopping carts and clothes.

For locals such as Randy Albro, the Silicon Valley sprawl is already hard to miss in small towns such as Patterson.

“It’s become what I would call a commuter city of the Bay Area,” said Albro, a 69-year-old air force veteran who lives at Patterson’s only homeless shelter, which has 16 beds.

Albro was raised on a nearby farm that grew “a little bit of everything”. After a legal dispute claimed the family home, he lived in his car with his son and his pit bull, Lady. When he was forced to retire as a funeral director, his fixed income left few market-rate options, while about 10,000 people in the county are already waiting for housing vouchers to help subsidize rent.

“You know an animal chasing its tail?” Albro said. “That’s what I feel like sometimes.”

Some of Albro’s friends have struggled, too, though a few with land have been able to sell their farms to housing developers. Just off a palmy thoroughfare not far from the Walmart that opened a few years ago, there is a development called Bella Flora. The 74 homes behind an ivy-adorned concrete wall start at $324,000, attracting roughly equal numbers of Bay Area and local prospective buyers, according to the realtor Eric Rodriguez.

“The Bay Area is a big part of our market,” Rodriguez said from his post at a 2,291-square-foot, four-bedroom, ranch-style model home christened The Covington.

Varying city and county estimates put Patterson’s homeless population at 60 to 80 people at a minimum on any one night, up from fewer than 20 people only three years ago. The numbers are small compared to San Francisco or Los Angeles, but for Patterson they are unprecedented.

In the county at large, about 1,400 homeless people were tallied during the last count and another 18,000 are considered “imminently homeless”, sleeping in cars, motels or couch surfing.

“We could probably build a new facility and fill it today,” said Kevin Carroll, executive director of a shelter in Modesto, the county seat, about 20 miles away. He turns away two dozen women and children a month due to a lack of beds. “This is a perfect storm.”

Services are limited in Patterson, which is unsurprising given that it doesn’t even have its own police department (and contracts instead with the county sheriff). Religious groups have tried to fill the void for the homeless. A group called Trust in Jesus Cuisine, for instance, serves daily lunches in downtown’s sleepy North Park.

“There were no services,” said Gordon Barbosa, a churchgoer and a board member of the religious group that started the town’s shelter. “Our local government isn’t doing it,” he added, because it is too large a problem for the city to handle by itself, though he noted that it provided his own organization with funds to purchase the shelter and has granted additional money this year.

On a recent Saturday, Devani Riggs and a friend set out to make their own money. They lugged three heavy barrels of bottles and cans to the local recycling center.

It’s a far cry from the waitressing job she loved at the regionally famous Pea Soup Andersen’s restaurant in her nearby hometown, Gustine. She lost the family’s $750-a-month, three-bedroom home after her mother died and her heroin use spiraled out of control. The “cages” were a desperate measure – they are totally open on top, rendering the occupants susceptible to rain and to unwelcome visitors scaling the sides.

Riggs’ recycling haul was weighed, and she cashed out.

“I’m getting my tax return next week,” she said. She hoped it would be enough to start over in a city where, just over the mountains from a tech boom, the barriers to entry are ever higher.

• The article was updated on 13 April to amend the spelling of Randy Albro’s surname. The spelling was originally confirmed to the Guardian as Albrea.
  
• This article was updated again on 25 April to clarify Gordon Barbosa’s comments on services in Patterson.