PORTLAND RESIDENT Caroline Sojourner signed a lease last year for $750 a month. On August 1, when it's time to renew, that price will jump to $1,087.

Sojourner can't afford the $337 a month increase, and says she's been sick with worry that she's going to have to move from her Brooklyn neighborhood apartment.

"I'm not the only one this is happening to," she says. "It looks like if I stay in Portland, I'm going to have to move every year because of the constantly rising rents."

Sojourner's not one of the twentysomethings flocking to Portland from California or out East; she's a senior citizen who receives help with her rent via housing vouchers from Home Forward, the agency overseeing public housing for Multnomah County. In this hot market, that help often isn't enough for those struggling to pay their bills.

Shelley Marchesi, a spokesperson for Home Forward, says the program has paths to help people in situations similar to Sojourner's—but as rents skyrocket, many Portlanders who are without safety nets are losing their homes because, as the saying goes, the rent is too damn high.

Senior citizens in Portland, on average, have a median income of $37,299 a year, according to Portland Housing Bureau (PHB) data. Of the Rose City's 24 "neighborhood analysis areas," only nine have median rent prices for a two-bedroom residence that would be considered affordable—meaning rent, not including utilities, is 30 percent or less of a tenant's income—to the average senior.

All told, more than half of renters in Multnomah County spend 30 percent or more of their income on housing, according to data reported by City Club of Portland.

"In Portland, the fair market rent for a two-bedroom apartment is $944," the City Club report says. "To afford this rent, a person would need to work 78.5 hours a week at minimum wage."

Seniors, of course, are just one of many groups finding it increasingly difficult to live in Portland. Communities of color and households headed by single mothers are, unsurprisingly, disproportionately affected by Portland's lack of affordable housing. A recent study by Governing magazine named Portland the nation's fastest-gentrifying city.

PHB's first "State of Housing in Portland" report, published in April, indicates there are zero neighborhoods in town where the average working African American or Native American household can afford a two-bedroom apartment. A single mother in Portland who earns the median annual income of $33,772 has a choice of two sectors of town where she might be able to afford to raise her family—both in East Portland.

"We're processing 300 rent increases every month," says Jill Smith, Home Forward's chief operations officer.

Smith says rents are climbing so high, and vacancy rates have become so tight, that nearly 25 percent of families who have waited—sometimes up to three years—on Home Forward's list to receive rent assistance aren't able to find apartments they can afford within the allotted 120-day timeframe.

"It's really frustrating for them, and for us," she says. "We're only at a 75 percent success rate right now, and it hasn't been that low since the 1990s."

When voucher recipients aren't able to find suitable housing within the 120-day window, they lose their vouchers, have to reapply, and go to the bottom of the waiting list.

"It's usually a pretty joyous occasion when a family gets their vouchers," Marchesi says. "So it's heartbreaking for everyone involved when they have to return the vouchers unused. We like our success rate to be in the upper 80s to low 90 percent range."

Rents in the Portland metro area rose an average of 20.45 percent since 2009, according to a recent study conducted by the National Association of Realtors. By comparison, average wages for the area during the same time period increased by 19.53 percent.

"It's really crazy right now," Smith says. "It really is a landlord's market."

A January study published by Zillow says Portland's average apartment is $1,587 a month in rent, a 7.2 percent year-over-year increase. And, thanks to the Oregon Legislature, cities and counties are prohibited from enacting rent control ordinances.

"We're seeing a particular demographic—people with dual incomes and no kids—really affecting Portland's rental market," says Justin Buri, executive director of Portland's Community Alliance of Tenants. "Those upwardly mobile tenants, who are willing to pay a little more, are a prized demographic for landlords."

Because of Oregon's preemption on rent control, landlords' only rules are that rent increases cannot be discriminatory (for only families of color, for example), and they cannot be retaliatory (in response to a repair request, for example), Buri says.

"There are very few options for renters because they have no leverage in this market," Buri says. "People are having to make some really hard choices."