Seattle Mayor Ed Murray recently announced a plan to raise the minimum wage in his city to $15/hour over the next few years. The plan emerged from a special business/labor advisory committee, approved by 21 out of 24 its members, after four months of hearings, academic studies, and debate . The measure awaits approval by the City Council, but the move to $15/hour in Seattle seems well underway.

Seattle may be the first, but it won’t be the last, city to take this bold step. Granted, there were some peculiarities in Seattle’s case, including a $15/hour minimum wage ballot initiative that succeeded in the nearby city of SeaTac in November, and the election of a new Socialist Party Seattle City Council member who campaigned on the issue. But with inequality taking center stage as a political issue in big cities around the country, mayors, businesses, and labor advocates are watching Seattle closely.

However, the focus on big cities shouldn’t obscure the fact that wages are a function of regional economics. Seattle is indeed a big city, with 635,000 residents and (by our count) nearly 500,000 jobs. But it’s only part of King County, Washington, which has roughly 2 million residents and more than 1 million jobs. And King County is just one of three counties that make up the wider Seattle metropolitan area, with a population of 3.5 million and 1.8 million jobs.

While low-wage jobs are prevalent in Seattle, they’re even more prevalent in its nearby suburbs. Using data from the American Community Survey, my colleague Sid Kulkarni and I calculated that between 2009 and 2011, there were on average 149,000 jobs (full-time and part-time) in the city of Seattle that paid less than $15/hour. Over the same period, the remainder of King County had an average of 216,000 jobs that paid hourly wages below that threshold. These low-wage jobs represented 30 percent of all jobs in Seattle, and 34 percent of all jobs in the rest of King County.

It stands to reason that low-wage jobs are more suburban than high-wage jobs. Typically, the highest-value jobs in a region are located in central cities. High-paying sectors like finance, advanced health care, information technology (Redmond notwithstanding), and higher education tend to be more urban than suburban. Yes, cities also have lots of low-paying jobs in hospitality and retail, but so do suburbs. Those jobs tend to follow people, and most people in major metro areas live in suburbs. As my colleague Elizabeth Kneebone has found, as population sprawls, so does low-wage work.

To be sure, many people who live in the King County suburbs of Seattle will benefit from a $15/hour Seattle minimum wage, because they work in the city. According to a University of Washington study conducted for Mayor Murray’s Income Inequality Advisory Committee, fully four in 10 people who earn less than $15/hour working in Seattle jobs—and who would thus presumably benefit from the minimum wage increase—live outside of the city. That’s particularly important in a region like Greater Seattle, where suburbs are home to most of the poor. At the same time, the UW study finds that nearly as many Seattle residents in sub-$15/hour jobs work outside the city limits.

None of this amounts to an argument against Seattle taking the first step toward increasing its minimum wage. Residential and commercial demand is so strong in the city these days that Seattle may have more latitude than its suburbs to boost its minimum wage significantly without encountering negative employment effects. And maybe the city needs to move first in order to convince its neighbors (and itself) that a $15/hour minimum wage won’t make the sky fall.

But these statistics offer an important reminder that the problems of low wages, inequality, and social mobility do not stop at city borders. Ultimately, more cities might try acting in coordination with their surrounding jurisdictions, as the District of Columbia did with two Maryland counties, to boost their minimum wages and ameliorate any “border effects.” And as Seattle contemplates other key policy initiatives, like universal preschool and backfilling state cuts to transit funding (a King County ballot initiative failed last month), it should keep open the lines of communication with its neighbors, and act as one county—or region—where it can.

Seattle Mayor Ed Murray recently announced a plan to raise the minimum wage in his city to $15/hour over the next few years. The plan emerged from a special business/labor advisory committee, approved by 21 out of 24 its members, after four months of hearings, academic studies, and debate . The measure awaits approval by the City Council, but the move to $15/hour in Seattle seems well underway.

Seattle may be the first, but it won’t be the last, city to take this bold step. Granted, there were some peculiarities in Seattle’s case, including a $15/hour minimum wage ballot initiative that succeeded in the nearby city of SeaTac in November, and the election of a new Socialist Party Seattle City Council member who campaigned on the issue. But with inequality taking center stage as a political issue in big cities around the country, mayors, businesses, and labor advocates are watching Seattle closely.

However, the focus on big cities shouldn’t obscure the fact that wages are a function of regional economics. Seattle is indeed a big city, with 635,000 residents and (by our count) nearly 500,000 jobs. But it’s only part of King County, Washington, which has roughly 2 million residents and more than 1 million jobs. And King County is just one of three counties that make up the wider Seattle metropolitan area, with a population of 3.5 million and 1.8 million jobs.

While low-wage jobs are prevalent in Seattle, they’re even more prevalent in its nearby suburbs. Using data from the American Community Survey, my colleague Sid Kulkarni and I calculated that between 2009 and 2011, there were on average 149,000 jobs (full-time and part-time) in the city of Seattle that paid less than $15/hour. Over the same period, the remainder of King County had an average of 216,000 jobs that paid hourly wages below that threshold. These low-wage jobs represented 30 percent of all jobs in Seattle, and 34 percent of all jobs in the rest of King County.

It stands to reason that low-wage jobs are more suburban than high-wage jobs. Typically, the highest-value jobs in a region are located in central cities. High-paying sectors like finance, advanced health care, information technology (Redmond notwithstanding), and higher education tend to be more urban than suburban. Yes, cities also have lots of low-paying jobs in hospitality and retail, but so do suburbs. Those jobs tend to follow people, and most people in major metro areas live in suburbs. As my colleague Elizabeth Kneebone has found, as population sprawls, so does low-wage work.

To be sure, many people who live in the King County suburbs of Seattle will benefit from a $15/hour Seattle minimum wage, because they work in the city. According to a University of Washington study conducted for Mayor Murray’s Income Inequality Advisory Committee, fully four in 10 people who earn less than $15/hour working in Seattle jobs—and who would thus presumably benefit from the minimum wage increase—live outside of the city. That’s particularly important in a region like Greater Seattle, where suburbs are home to most of the poor. At the same time, the UW study finds that nearly as many Seattle residents in sub-$15/hour jobs work outside the city limits.

None of this amounts to an argument against Seattle taking the first step toward increasing its minimum wage. Residential and commercial demand is so strong in the city these days that Seattle may have more latitude than its suburbs to boost its minimum wage significantly without encountering negative employment effects. And maybe the city needs to move first in order to convince its neighbors (and itself) that a $15/hour minimum wage won’t make the sky fall.

But these statistics offer an important reminder that the problems of low wages, inequality, and social mobility do not stop at city borders. Ultimately, more cities might try acting in coordination with their surrounding jurisdictions, as the District of Columbia did with two Maryland counties, to boost their minimum wages and ameliorate any “border effects.” And as Seattle contemplates other key policy initiatives, like universal preschool and backfilling state cuts to transit funding (a King County ballot initiative failed last month), it should keep open the lines of communication with its neighbors, and act as one county—or region—where it can.

Drive through any number of outer-ring suburbs in America, and you’ll see boarded-up and vacant strip malls, surrounded by vast seas of empty parking spaces. These forlorn monuments to the real estate crash are not going to come back to life, even when the economy recovers. And that’s because the demand for the housing that once supported commercial activity in many exurbs isn’t coming back, either.

By now, nearly five years after the housing crash, most Americans understand that a mortgage meltdown was the catalyst for the Great Recession, facilitated by underregulation of finance and reckless risk-taking. Less understood is the divergence between center cities and inner-ring suburbs on one hand, and the suburban fringe on the other.

It was predominantly the collapse of the car-dependent suburban fringe that caused the mortgage collapse.

In the late 1990s, high-end outer suburbs contained most of the expensive housing in the United States, as measured by price per square foot, according to data I analyzed from the Zillow real estate database. Today, the most expensive housing is in the high-density, pedestrian-friendly neighborhoods of the center city and inner suburbs. Some of the most expensive neighborhoods in their metropolitan areas are Capitol Hill in Seattle; Virginia Highland in Atlanta; German Village in Columbus, Ohio, and Logan Circle in Washington. Considered slums as recently as 30 years ago, they have been transformed by gentrification.

Simply put, there has been a profound structural shift — a reversal of what took place in the 1950s, when drivable suburbs boomed and flourished as center cities emptied and withered.

The shift is durable and lasting because of a major demographic event: the convergence of the two largest generations in American history, the baby boomers (born between 1946 and 1964) and the millennials (born between 1979 and 1996), which today represent half of the total population.

Many boomers are now empty nesters and approaching retirement. Generally this means that they will downsize their housing in the near future. Boomers want to live in a walkable urban downtown, a suburban town center or a small town, according to a recent survey by the National Association of Realtors.

The millennials are just now beginning to emerge from the nest — at least those who can afford to live on their own. This coming-of-age cohort also favors urban downtowns and suburban town centers — for lifestyle reasons and the convenience of not having to own cars.

Over all, only 12 percent of future homebuyers want the drivable suburban-fringe houses that are in such oversupply, according to the Realtors survey. This lack of demand all but guarantees continued price declines. Boomers selling their fringe housing will only add to the glut. Nothing the federal government can do will reverse this.

Many drivable-fringe house prices are now below replacement value, meaning the land under the house has no value and the sticks and bricks are worth less than they would cost to replace. This means there is no financial incentive to maintain the house; the next dollar invested will not be recouped upon resale. Many of these houses will be converted to rentals, which are rarely as well maintained as owner-occupied housing. Add the fact that the houses were built with cheap materials and methods to begin with, and you see why many fringe suburbs are turning into slums, with abandoned housing and rising crime.

The good news is that there is great pent-up demand for walkable, centrally located neighborhoods in cities like Portland, Denver, Philadelphia and Chattanooga, Tenn. The transformation of suburbia can be seen in places like Arlington County, Va., Bellevue, Wash., and Pasadena, Calif., where strip malls have been bulldozed and replaced by higher-density mixed-use developments with good transit connections.

Reinvesting in America’s built environment — which makes up a third of the country’s assets — and reviving the construction trades are vital for lifting our economic growth rate. (Disclosure: I am the president of Locus, a coalition of real estate developers and investors and a project of Smart Growth America, which supports walkable neighborhoods and transit-oriented development.)

Some critics will say that investment in the built environment risks repeating the mistake that caused the recession in the first place. That reasoning is as faulty as saying that technology should have been neglected after the dot-com bust, which precipitated the 2001 recession.

The cities and inner-ring suburbs that will be the foundation of the recovery require significant investment at a time of government retrenchment. Bus and light-rail systems, bike lanes and pedestrian improvements — what traffic engineers dismissively call “alternative transportation” — are vital. So is the repair of infrastructure like roads and bridges. Places as diverse as Los Angeles, Phoenix, Salt Lake City, Dallas, Charlotte, Denver and Washington have recently voted to pay for “alternative transportation,” mindful of the dividends to be reaped. As Congress works to reauthorize highway and transit legislation, it must give metropolitan areas greater flexibility for financing transportation, rather than mandating that the vast bulk of the money can be used only for roads.

For too long, we over-invested in the wrong places. Those retail centers and subdivisions will never be worth what they cost to build. We have to stop throwing good money after bad. It is time to instead build what the market wants: mixed-income, walkable cities and suburbs that will support the knowledge economy, promote environmental sustainability and create jobs.