The cities of the North American West Coast share so much as vibrant, sustainable and prosperous places to live and work in the 21st century. However, our success is no accident; through thoughtful city planning, San Francisco and the greater Bay Area, Portland, Seattle and Vancouver, British Columbia, are cities that are the envy of the world.

We also face a common threat to that livability. We are seeing unprecedented escalation in housing costs for our working families, the “missing middle” and young professionals, as well as the increasing pressure on our most vulnerable populations.

San Francisco is not alone in this. In Vancouver, the cost of housing has rapidly escalated beyond the earning power of the average resident. To find solutions, we’ve reached out to learn from the experiences and experiments of our fellow West Coast cities, as well as international cities, including Vienna, London, Sydney and New York.

We’ve learned the causes of the housing crisis are deep and powerful: housing is increasingly not “home” first but rather a commodity for investment on a global market for investors large and small, foreign and local, as interest rates remain low and equity searches for substantial returns. Who can blame the couple with equity to invest for buying a house or a condo that in a few years might double their return and provide a nest egg? For larger real estate interests, building and selling at the top of an ever upward-moving market or “reno-victing” tenants to increase rents are a matter of “rational” market behavior.

As attractive cities with decades of intentional investment in urban livability under our belts, we now face a historic return of populations to the urban core of our regions. For Baby Boomers and Millennials alike, our city cores are the preferred place to live, reversing six decades of a widespread suburbanization trend. Land prices now reflect that inward surge.

Finally, and this may be most prevalent in San Francisco, there is the growing income disparity between the new-economy employees and our traditional residents. This disparity creates a class issue that tears at the fabric of neighborhoods as traditional communities, such as the Mission District or Vancouver’s Chinatown, struggle in the face of an influx of wealth.

In Vancouver, we hope to get ahead of the same pressures San Francisco is facing. We’re taking action to limit speculative investment and put our housing stock to its best use by implementing Canada’s first Empty Homes Tax, a 1 percent annual tax on empty or underused residential properties. We are preparing an ambitious 10-year housing strategy to lay the foundation for a diverse and equitable city. It starts with the notion that supply is not the issue — we have produced lots of housing over the past decade — but rather lack of the “right supply.”

For many years, Vancouver’s new housing was focused on condominiums and similar developments. Now, Vancouver will try to deliver housing that meets local needs and incomes of our residents: a housing mix that includes more rental housing, townhomes, row houses and duplexes in low- and moderate-density neighborhoods.

As a city similar to San Francisco with a finite supply of land, Vancouver will rely on density bonuses to augment our inclusionary housing requirements, as the primary tools to incentivize developers to provide the range of rental housing we need. We are also looking across all of our neighborhoods — from transit station areas and major corridors to single-family neighborhoods — for creative infill opportunities that maintain the character of these neighborhoods while providing new homes. These opportunities might include duplexes, row homes, town houses and more.

We’re also looking to new approaches such as co-housing and innovative homeownership models to deliver some of this housing.

Finally, we are offering $195 million worth of city-owned land, with proceeds from senior (federal and provincial) governments, to ramp up production of housing that serves the lowest-income residents. Those efforts include expanding well-designed modular and prefabricated housing, which can be constructed in as little as six months.

Overall, we seek to produce over the next decade about 7,000 new homes per year affordable to various household sizes and income levels, and not exceeding 30 percent of the household income on housing costs. Like San Francisco, our greatest reservoir of affordable housing is actually already built and rented by working singles and families, students and elderly residents on fixed incomes. We will need to look at ways to secure or replace much of that as affordable long-term rental stock.

We believe it is time for our mayors and planning directors to formalize a working West Coast Collaborative to tackle this and other issues facing our beautiful and prosperous cities, to share experiences and learn from each other as we advance our efforts to remain just and sustainable places. We hope you will join us.

Gregor Robertson is the mayor and Gill Kelley is the chief planner of Vancouver, British Columbia. To comment, submit your letter to the editor at SFChronicle.com/letters.

The housing-income disconnect Vancouver, British Columbia

$56,474 (in U.S. dollars)

Median total household income (2015)

$1.119 million

Median single-family home price

(3Q, 2017)

San

Francisco

$88, 518

Median total household income (2015)

$1.130 million

Median single-family home price

(3Q, 2017)