By Andrew Keatts.

Turns out, the city of San Diego is mostly a suburb.

That might not come as a total surprise to many residents — some of whom presumably moved here because, well, the city is less of a city than other cities.

San Diego’s largely suburban nature was one of the findings when Jed Kolko, former chief economist at real estate website Trulia, last month sought to quantify how much of the country’s largest cities were actually built more like suburbs.

Trulia surveyed 2,000 residents on whether they considered their neighborhoods suburban, urban or rural. They didn’t define the terms because they hoped to learn about people’s perceptions of them.

It then compared the responses to the characteristics of each ZIP code and found people generally consider their neighborhoods urban if they have more than 2,213 households per square mile. That is, people’s perceptions lined up really well with the population density of their neighborhoods. It then used density to establish a cutoff between each classification and put each ZIP code into an urban, suburban or rural bucket.

Just three of the country’s 10 largest cities were predominantly suburban: San Diego, Phoenix and San Antonio. Just 49 percent of San Diego’s land area is what Americans tend to consider “urban,” Kolko found.

Even Los Angeles, another car-centric Southern California city, was 87 percent urban. Traditional East Coast cities like New York and Philadelphia were almost entirely urban.

A map of San Diego coded to show the different classifications looks about how you might expect. It shows that, indeed, a huge swath of the city is what most people consider a suburb.

Kolko said not to dwell too closely on specific ZIP code classifications.

“The classification (of each ZIP code) is a prediction of how local residents probably think of their neighborhood based on the neighborhood measures that tend to be associated with urban, suburban and rural areas,” he wrote in an email.

Most important, Kolko said, is the broad point that large areas within the boundaries of the country’s largest cities aren’t all that urban.

The map of San Diego, broken down by suburban and urban areas, shows how difficult some of the planning and transportation challenges facing the city are, said Nicole Capretz, executive director of the Climate Action Campaign, a group pushing local cities to adopt plans that would decrease their long-term carbon footprint, and the primary author of the city’s proposed Climate Action Plan.

“What it really shows is that to really cut greenhouse gas emissions by 50 percent by 2035, it will require incredible leadership to have candid conversations that will change our land use and transportation decisions, that would make it easier to live close to where people work,” Capretz said.

Those conversations aren’t happening, she said, and the map shows that the city has a lot of work to do to create the sort of urban villages that it says are its goal for future growth.

Bruce Appleyard, professor of urban planning at San Diego State University, said there are two ways to look at the city’s large share of suburban neighborhoods.

San Diego is large and includes a wide range of different types of neighborhoods, each with different priorities and problems. That separates it from a place like San Francisco, which is small enough that most of its neighborhoods are similarly urban.

“An important part of urban planning is to make sure you have a clear sense of purpose and direction on where and how you want to grow and evolve,” Appleyard said. “That can be difficult when you’re trying to satisfy the needs of many different urban and suburban place types, with areas needing different and appropriate strategies.”

He pointed to three recent examples. In Barrio Logan, local residents pushed for a new long-term development plan only to see it get overturned by a citywide vote. In Uptown, a group of motivated business owners effectively killed a plan to build major bike infrastructure through the community. And in Bay Park, the city’s plan to increase development around a new trolley station fell to local opposition.

“At a certain point, politicians need to have some resolve,” he said. “We have very good, skilled planners who pursue broad goals and objectives and they need to be supported by politicians.”

At the same time, though, he said the relatively large geographic area that’s part of the city’s official boundaries can be a strength. Instead of having a bunch of small towns making up the northern reaches of the city, San Diego has a single political body making decisions for the whole area, which can allow it to act more strategically on regional needs.

“Right now, we aren’t taking advantage of that benefit,” Appleyard said.

Nonetheless, he said splitting the ZIP codes into suburban, urban and rural classifications doesn’t go far enough. There are a number of more granular classifications that show the different characteristics of neighborhoods.

He provided an example of a look at the central part of San Diego that measures how urban an area is not just by housing density, but also how well connected it is by transportation options, and how many destinations there are that might drive people to the area.

By that standard, you can get a better sense of the different development patterns across the city.