Two trends are working in Portland’s favor. If the city can take advantage of them, it may have found a new way to prosper.

One is the slow-growing economy, in which decades of stagnant wage growth have led some consumers to think they have to find a way to spend more carefully.

The other is the lifestyle choice by a growing number of young people who prefer to live without a car, whether they can afford one or not.

As one of the few places in New England and probably the only place in Maine where people can live, work, attend school, run errands, visit doctors and dentists and enjoy indoor and outdoor recreation without driving, Portland becomes a more attractive place to live.

Car registration trends show this is already happening. From 2004 to 2011, the number of registered passenger vehicles has declined in the city by 23 percent even as the population has grown. Registrations have dropped statewide and nationally as well, but not at such a significant rate.

This may be why Portland apartments have such a low vacancy rate — 2.5 percent, which is tied for the second lowest in the nation.

City policy could help continue the trend.

There is demand for housing in walkable districts. The city could make more available by relaxing parking requirements that assume every resident will have at least one car. That would lower the cost of development and encourage a denser style of development that would let more people take advantage of an urban lifestyle affordably.

The city should also continue to push for better transportation alternatives that will make the city more attractive to people who want to live without cars. That means improving pedestrian and bicycle access to services from the off-peninsula neighborhoods. It also means taking serious steps toward improving public transit.

City Councilor David Marshall has proposed a study of streetcar service for the city. That shouldn’t sound far-fetched in light of the decline in car usage.

Owning a car is estimated to cost $9,000 a year. When people think about how else they could spend that much money if they didn’t have to own a car, Portland becomes that much more attractive. City officials should recognize this fact and take advantage of it.