With the days getting shorter and the temperatures colder, it's sobering to think that on any given night more than half a million Americans are homeless. In the last three years, according to government reports, cities on the West Coast have seen a dramatic rise in the number of people who are "unsheltered." That's the term used to refer to anyone who's homeless, but not sleeping in a shelter. They're the people you see sleeping on streets or in parks, in tent encampments, or in vehicles. Why has the unsheltered population been going up at a time of economic expansion and low unemployment? One answer is rising rents in hot real estate markets. Take Seattle and surrounding King County, which are booming thanks to high-tech companies but now have the third highest number of homeless people in the country. The Seattle area is home to Amazon and Microsoft, but also to a homeless encampment called Tent City Three.

In the shadow of Interstate 5 in Seattle, on a vacant strip of public land, this is Tent City 3. There are about 50 people living here, without heat or running water.

Ethan Wood is celebrating his third birthday. He's lived in a tent for the past year and a half.

His parents, Tricia and Josiah, told us Ethan has an enlarged heart and suffers from bouts of asthma and croup so severe, they've had to take him to the emergency room several times. Last winter, one of Seattle's coldest in recent memory, Ethan was sleeping in a tent, covered with blankets, sandwiched between his parents for warmth.

Anderson Cooper: Did you ever think, "Well, this is not the place, we should have our child"?

Josiah Wood: We don't want our son here. We don't want to be here. But as of right now, this is the safest place for us.

Tricia Wood: Absolutely.

Josiah Wood: Because we know the people, we know the rules, and--

Tricia Wood: Our family gets to stay together.

Josiah Wood: And our family stays together.

Ethan, Josiah and Tricia Wood

Drug addiction is what led the Woods to become homeless. For Josiah it was meth, for Tricia, heroin. They were living in Alaska at the time. Josiah's parents took care of Ethan while they both got treatment. Tricia came to Seattle for rehab and afterwards decided it was a good city for a fresh start. They say they haven't used drugs in nearly two years, but it's been hard to find housing. In May 2018, they tried to get a spot in one of Seattle's family shelters, but there was no room. They didn't want to split up into separate shelters -- one for men, and another for women with children -- so they found their way to Tent City Three and decided to stay.

This is one of several makeshift encampments in Seattle that are allowed by the city. Decisions are made by camp residents, who are also required to do chores and take turns guarding the tents. But about every three months, all the residents in Tent City Three agree to pack up and move to a new location. It's an arrangement they make with the landowners who let them pitch their tents. No one wants a camp of homeless people in their neighborhood for very long.

When we visited Ethan and his parents in September, they had just packed up their tent near the highway and were setting up in a church pastor's backyard. It was the eighth time they've had to move in the past year and a half.

Anderson Cooper: Someone we talked to said that it-- it's a lot of work being homeless -- that people don't realize that.

Tricia Wood: It is-- It is a ton of work being homeless.

Josiah Wood: It is a lot of work.

Anderson Cooper: Ex-- explain.

Josiah Wood: We go to a downtown place called Urban Rest Stop for a shower and laundry.

Anderson Cooper: How far away is that?

Tricia Wood: From here, that's a 45-minute--

Josiah Wood: 45-minute bus ride.

Anderson Cooper: --you take a 45-minute bus ride in order to go take a shower?

Josiah Wood: Just to go take a shower.

Tricia Wood: And then wait maybe for 45 minutes to an hour and a half to take that shower. You know, nobody ever plans to live in a tent, ever. So...

Anderson Cooper: You never thought—

Tricia Wood: Never.

Josiah Wood: We never thought we'd be here. Until something hits you so hard that it just sweeps your feet out from underneath you completely, you can't prepare for it.

Tricia Wood: I used to be one of those people that thought that if anyone was homeless they just needed to go get a job. That would solve their homeless problems.

Anderson Cooper: How would you answer that question now? Why can't they just get a job?

Tricia Wood: Oh my goodness. Maybe they have a job.

Josiah Wood has a full-time job. He gets up before dawn and takes mass transit to work as a maintenance supervisor at the Hard Rock Café downtown. Though he makes $19.50 an hour, the rent for an average one-bedroom apartment in Seattle would eat up half his salary. He and Tricia say they've been saving up money so they can afford a security deposit and monthly rent.

Anderson Cooper: How long do you think you'll keep living in the tent city?

Tricia Wood: I would hope we are out of here by winter.

Josiah Wood: We will be out of here by winter. I'm not going to allow my family to suffer again in the winter.

Emilee Broll

Emilee Broll also lives in Seattle. She's been delivering mail for the U.S. Postal Service for nearly five years.

In her uniform, you'd never know she too is unsheltered. She lives in a rickety old RV parked by the side of the road, which meets the government's definition of homelessness. More than 2,000 people in the Seattle-King County area live in some kind of vehicle. Emilee Broll's Dodge Commander is 42 years old.

Anderson Cooper: Why are you living in an RV?

Emilee Broll: Because rent is obscene here. I can't afford it. I just think I'm working my butt off. And I don't want to just spend all of my money paycheck to paycheck just to survive.

Anderson Cooper: Given the work you do, I think most people would think, "Well, that's a job that one can live off."

Emilee Broll: Yeah. I think a lot of people are shocked when they find out that I'm-- I work full time.

Anderson Cooper: What's the solution here?

Emilee Broll: Affordable housing, build it. Quit selling out to developers.

Housing prices in Seattle skyrocketed more than 60% over the last five years as hi-tech companies expanded or moved in. Jeff Gold was unable to pay the rent on his apartment and was evicted nearly six years ago. When we met him in August, he'd just started a new job as a database coordinator. He was 58 years old and a graduate of the University of Illinois. This is where Jeff was sleeping -- beside a church, on a sheet of cardboard. Each morning, he gathered his few possessions, stuffed them in a plastic bag, and stored them in a friend's truck. Then he headed for work at the Environmental Protection Agency.

Jeff Gold

Anderson Cooper: Do people at work know that you're homeless?

Jeff Gold: No. I had a meeting with my boss yesterday and I thought long and hard. Like, there was a moment where, like, "Should I come out?"

During our interview, Jeff smelled of liquor and by his bed, there were empty bottles of vodka -- a step up, he says, from the alcohol he normally would buy with food stamps.

Anderson Cooper: How do you get alcohol with food stamps?

Jeff Gold: Cooking sherry.

Anderson Cooper: You can get cooking sherry--

Jeff Gold: It's the only alcohol you can buy on food stamps.

Anderson Cooper: Do you think you have an-- addiction issue with alcohol?

Jeff Gold: Oh, I am definitely an alcoholic.

Anderson Cooper: Have you tried to stop? Or do you want to stop?

Jeff Gold: No. For me, I-- I pretty much have it under control, in the sense that I guess I-- I get to work every morning.

Anderson Cooper: I mean, you're sleeping outside on rocks with your possessions in a bag so it's not all under control.

Jeff Gold: I'm movin' forward. I got paid a couple of days ago.

In all, there are about 11,000 homeless people in the Seattle-King County area, according to the latest government count. They make up roughly 1% of the city's population, but last year they accounted for nearly 20% of those arrested and jailed, mostly for non-violent offenses ranging from theft and loitering to drug violations. At a city council meeting last year, it became clear many residents have had enough.

Ari Hoffman

Ari Hoffman: It's out of control.

Ari Hoffman is a Seattle businessman and a former candidate for city council.

Ari Hoffman: When you're coming to coach baseball, like I do, and you have to clean needles off the fields…

Anderson Cooper: You actually have to clean needles off the--

Ari Hoffman: Oh, sure and there are sometimes people sleeping in the dugouts.

Anderson Cooper: What do you think is to blame for it?

Ari Hoffman: You need to stop talking about it like it's a housing affordability issue and start talking about it like it's a drug problem.

Dennis Culhane: Seattle ten years ago didn't have this level of homelessness. Where were these people then? They haven't changed. These folks have been here.

Dennis Culhane, a professor at the University of Pennsylvania, has been researching homelessness for 35 years. He doesn't believe drug addiction and mental illness explain why there's been a recent rise in the number of unsheltered people.

Anderson Cooper: Why is this happening?

Dennis Culhane: The best evidence we have is that it's the real estate market. You have a lot of wealthier individuals, especially in places like Seattle, who are driving up the price of housing and there's just not enough housing to filter down to the lower income people.

Dennis Culhane

Anderson Cooper: What about substance abuse, alcoholism, drug abuse?

Dennis Culhane: Substance abuse is particularly important for the people who are homeless for a longer period of time. It's much harder to get out if you have an addiction issue.

Professor Culhane says most people who become homeless in America are able to get out of it within a few months. But the more than 20% who remain homeless for a year or more are often the most visible, and the vast majority of them do suffer from mental illness, or drug or alcohol addiction.

Mayor Jenny Durkan: There is hope. We've seen things that actually reduce the number of people experiencing homelessness, but every person takes time-- and you have to have a strategy for that person.

Jenny Durkan is the mayor of Seattle. She says the city has added more than 500 shelter spots, taken down more than a thousand illegal encampments, and secured funding for 5,000 new, affordable housing units over the next three years. The city has also created what they call "enhanced shelters" that try to help people find permanent housing. And Mayor Durkan is looking for ways to stem the flow of new people who are becoming homeless.

Mayor Jenny Durkan: Too many people come right out of the criminal justice system into homelessness. And so if you work with the hospitals, the jails, the prisons, foster care system, and say, 'let's make sure people have shelter or housing before they go.'"

Anderson Cooper: Do you actually feel that the City has a grip on this problem?

Mayor Jenny Durkan: I think we know what works.

Anderson Cooper: I counted 12 people homeless right outside city hall right now. If the city knows what works, why are there still so many homeless people out there?

Mayor Jenny Durkan: Because it's so complex, there's no one city in America that's going to fix this. This has got to be both a regional and State-wide and federal answer.

Nationwide, there have been successes. Since the federal government committed money for housing subsidies and supportive social services for veterans, the number of homeless veterans has gone down 50% in the last 10 years.

In June, President Trump signed an executive order creating a council to come up with ways to cut down on regulations that make it expensive to build affordable housing. But the federal government has not allocated enough housing money to keep up with the crisis. Amazon and its founder, Jeff Bezos, have committed more than $300 million to help the homeless in Seattle and other parts of the country. Apple has pledged $2.5 billion in California. But professor Dennis Culhane says private donations will only go so far.

Dennis Culhane: A billion dollars sounds like a lot but, to solve the housing affordability gap is about a $30 billion requirement. And that's every year.

Anderson Cooper: Just for housing subsidies.

Dennis Culhane: Just for housing subsidies. But I should note that we spend about $12 billion a year just on the emergency shelter system, okay, which isn't solving people's homelessness. And even with that expenditure, you know, a third of the people still have no place to sleep.

The total number of homeless people in Seattle and King County went down by 8% this year according to the city, but there are still more than 5,000 people unsheltered in one of the wealthiest metropolitan areas in the country.

Last we heard from Jeff Gold, he'd been fired from his job at the EPA because of poor attendance.

Postal worker Emilee Broll has decided to leave Seattle and her RV for a place where housing is more affordable.

And 3-year-old Ethan Wood? He and his parents are still living in Tent City 3. They seem no closer to finding a home before winter.

Tricia Wood: Nobody really wants to rent to someone who's lived in a tent for the past year regardless of how well of a fit we would be for them. We have absolutely made mistakes in our lives. But that doesn't mean that we don't deserve to raise our family in a house that we can afford. We are more than willing to pay for it. We just need someone to give us a chance to do it.

Produced by Andy Court and Evie Salomon. Broadcast associate, Jacqueline Kalil.