North Park, one of San Diego’s earliest suburbs for the city’s burgeoning population a century ago, is the epicenter of another development trend: infill.

With most “greenfield” development sites filled up or spoken for in the county and the population continuing to grow, buyers and renters wonder where they’re going to live.

Apparently, many are heading to North Park, where developers are razing old buildings and erecting new ones, adapting existing structures for new uses or filling vacant lots with housing and shops.

Of course, infill isn’t new. It’s been going in San Diego ever since the first buildings were constructed in Old Town in the 1820s. Spaces between farm houses were filled by other houses and businesses in the 1880s. Then those single-story buildings were replaced by parking lots or denser development in the 1920s and since World War II, urban neighborhoods have seen single-family-home streets turn into multifamily developments.

The new twist on infill is that city and state policy to combat global warming, sprawl and transportation congestion is actively promoting transit-oriented developments, walkable neighborhoods and live-work-play planning. In short density is our destiny.

“Many cities struggle to accommodate their rising population growth and do not easily find space for new housing, schools, amenities and parks,” said an Urban Land Institute report released last year.

But the result does not have to consist of “slums, of concrete and of tower blocks.”

“They do not imagine Singapore, Paris, Barcelona, Toronto or Vienna, all examples of cities that successfully densified in order to survive,” wrote Greg Clark and Emily Moir in their report “Density: Drivers, dividends and debates.”

North Park planning at a glance North Park community plan 1986-2016 Non-residential Max. res. density Population Dwelling units million sq.ft. du/ac Present conditions 46,420 25,025 3.5 110 Current plan 68,160 34,295 3.2 110 Proposed plan 73,170 36,570 3.2 145 Change from 1986 plan 7.4% 6.6% 0.0% 31.8% Change from present 57.6% 46.1% -8.6% 31.8% City of San Diego Planning Department

So where does North Park fit in this trend?

The 1,980-acre neighborhood northeast of Balboa Park, is filled up with more than 46,000 residents and 3.5 million square feet of nonresidential development. It’s home to the historic North Park Theater, Lafayette Hotel, North Park Community Park water tower and dozens of historically designated homes and commercial buildings.

But drive along its major thoroughfares and byways and you’ll see scattered empty lots, marginal businesses and tired old apartment buildings.

“El Cajon Boulevard is very blighted, has unmet capacity,” said North Park Community Planning Group Chairwoman Vicki Granowitz. “We want livable communities where people can walk and bike.”

Granowitz is one of the key leaders pushing for passage of a new community plan, the first in 30 years, that would boost population to more than 70,300, only 5,000 more than contemplated in the 1986 plan.

But the difference is that growth would be concentrated along the transportation corridors of El Cajon Boulevard, University Avenue and 30th Street and take the pressure off side streets where zoning has allowed some houses to be replaced by undistinguished two-story apartment projects over the last 50 years.

“This is a plan for the future,” she said. “It’s not really for my generation. It’s for the generation that wants to live in North Park and can’t afford North Park.”

She could have been thinking of Matthew Lyons, 28. Last month he opened up Tribute Pizza in the former North Park Post Office at 3077 North Park Way and locals lined up out the door. The 10 parking spots often go begging because so many of his customers bike or walk to try out dishes like Molto Autentico pizza (topped with Calabrian chile sausage).

Lyons grew up in La Jolla, graduated from UC Merced and moved to North Park five years ago.

“I’m a food guy and maybe I’m drawn to the places where there’s the best food in town,” he said.

The location he chose was redeveloped into housing and commercial spaces by FoundationForForm, an architecture-development company headed by infill expert Mike Burnett. He’s won numerous design awards for distinctive concepts aimed at creating little communities of people who like to talk and party with one another.

“It seems the marketplace wants to be more walkable,” Burnett said. “That’s what’s driving developers to go to the more urban core.”

Burnett said he tries to avoid the not-in-my-backyard opponents to infill by adhering to existing zoning and avoiding plans that require discretionary permits. His latest project, The Earnest, is going up at 4201 30th and he’s designed a project for H.G. Fenton on the 2000-block of El Cajon Boulevard.

The 30-something Burnett says he’s thinking of millennials like Lyons who like small units and lots of common space and don’t necessarily need a parking space.

“It’s not the ‘Huffman box’ — they were terrible,” he said. “Those times are gone.”

The Huffman he was referring to is the late Ray Huffman, a developer who built some 600 apartment buildings with more than 7,000 units starting in 1962 in North Park, City Heights and other urban neighborhoods.

They represented the first wave of infill, as he tore down early 1900s craftsman bungalows and replaced them with six-, eight- or 10-unit apartments, blank walls facing the street and parking spaces on the former driveways, necessitating wide curb cuts and elimination of street parking. They’re often referred to as “Huffman six-packs.”

The new community plan includes provisions that would encourage owners of the Huffmans to tear them down and build something more attractive and with more units.

Ironically, Huffman, who died in 2001, hailed the return-to-the-city movement in 1985 declared that increased building density is San Diego’s destiny.

“Let certain areas become so densified that the people who live and work there don’t need automobiles,” he said in a guest column in The San Diego Union in 1985. “It works in parts of San Francisco, New York, Vienna and other cities. It can work here, too.”

Build up, not out, he said, and that’s the theme in the North Park plan and the “city of villages” policies embodied in San Diego’s general land use plan adopted in 2008.

The plan has lain largely dormant since the recession, but in the recovery, multistory projects have sprouted first downtown and then in North Park, Uptown and other neighborhoods.

Sometimes, as in the One Paseo project in Carmel Valley, neighborhood opposition is strong enough to force a redesign or developer to retreat.

But in North Park, new development has proceeded relatively smoothly, according to this summary by developer and former commercial real estate broker Danny Fitzgerald of Real Development:

▪ 906 apartment units built that he valued at $225 million completed since 2010

▪ a 40 percent increase in annual sales taxes to $2.8 million from 2010 to 2015, and

▪ a 176 percent increase to $580,160 in annual hotel room taxes in the last five years.

He called it an “economic development boom” that will help curb the current housing affordability and low-inventory problem through more construction.

Fitzgerald is currently working on a development at Park Boulevard and University Avenue that he hopes will yield as many as 80 units in place of an earlier plan for only 20 or 30 condos in a five- or six-story building.

“San Diego keeps growing with more jobs, and we’re not producing housing,” he said.

Borre Winckel, president and CEO of the San Diego County Building Industry Association, said the state as well as local governments are beginning to realize the consequences of slow growth in the face of rapid job creation.

“The only way we can make workforce housing available is by gaining slightly higher density than most neighborhoods have today,” Winckel said.

Density is usually measured in housing units per acre, and North Park’s plan would boost the lid along major corridors by nearly a third. Where 110 units of whatever size were previously allowed, a developer could now build 35 more.

But this would increase North Park’s population by only 5,000 over the previous ceiling of 68,000, according to city projections.

Of course, there are North Park residents who don’t welcome a new wave of development. Some worry that their single-family-home neighborhoods will suffer from increased traffic, higher crime and depressed property values.

Don Leichtling, 69, has lived in North Park for 30 years and says it’s becoming oversaturated with drinking establishments, and is “too bars-y and noisy at night.”

“We need to have a moratorium on new buildings over two stories until we get this (zoning) code thing worked out,” he said.

Andrew Malick, another architect-developer, completed North 30, a 10-unit apartment project at 4640 30th St. last year and when faced with a 12-year lease for an existing billboard, designed around it. There are three storefront spaces at ground level.

“That was better than the existing, dilapidated house that had fallen into disrepair,” he said.

And he’s scouting for new building sites in Chula Vista, San Marcos and Vista.

Ramon Astamendi, 39, is one of his tenants who embraces the live-work-play potential of North Park. He’s one block north of his Fall Brewing company and can steal away for a midday nap if necessary. He pays $1,500 for a 600-square-foot, top floor unit.

“What won me over was North Park had a lot of like-minded businesses that came in and took a risk, in a neighborhood that at that point wasn’t a main destination,” he said.

He recognizes some North Parkers’ concerns, but leaves it to the market to determine the proper balance between supply and demand.

City Planning Director Jeff Murphy said North Park’s new plan, headed for City Council approval this fall, has attracted relatively little opposition after eight years of preparation because of grassroots support for more growth and the prospects of general community upgrade.

“Growth is not necessarily scary,” he said. He’s seeking other examples of good design to share with other skeptical neighborhoods. “It’s not necessarily density they’re concerned about — it’s what the buildings look like.”