Prompted partly by the success in luring Amazon, 10 Northern Virginia jurisdictions have formed an alliance to market themselves as a region to attract other companies, especially those in the high-tech arena.

Instead of trying to poach businesses from each other, or promote themselves at their neighbors’ expense, they will compete mainly as a group against other major metropolitan areas such as Boston and Silicon Valley to lure companies from outside the Washington area.

The new Northern Virginia Economic Development Alliance, or NOVA EDA, was formally announced Monday. It will include Fairfax, Arlington, Loudoun, Prince William and Fauquier counties, and the cities of Alexandria, Fairfax, Falls Church, Manassas and Manassas Park.

Officials said the collaboration will strengthen Northern Virginia’s appeal to potential investors at a time when the area has attracted international interest because of Amazon’s high-profile decision to build its second headquarters, with 25,000 high-paying jobs, in Arlington’s Crystal City.

Although a memorandum of understanding signed by the 10 jurisdictions still allows them to act individually — and potentially compete as in the past — officials said they see numerous benefits in cooperating.

“Look at how successful this region has been in its own fractured way,” said Christopher Bruno, economic development director for Fairfax City. “Imagine how successful it can be now that we’re all pulling in the same direction.”

The move also appeared likely to add to Northern Virginia’s economic advantages over the District and the Maryland suburbs. Even before the Amazon decision in November, Northern Virginia accounted for well over half of the new jobs created in the Washington metropolitan area. That’s due to a mix of factors, including a lower corporate tax rate, weaker labor unions and better access to airports.

It wasn’t clear whether the initiative would help or set back efforts by organizations such as the 2030 Group and Greater Washington Partnership to forge a regional identity that bridges the Potomac to unite Northern Virginia with the District and suburban Maryland.

The new alliance’s members will be the top economic development officers of each jurisdiction. They will develop and market a regional brand, and unite for trips to business conferences and visits with corporate decision-makers.

The alliance also will deal with the Virginia Economic Development Partnership, the state authority tasked with luring businesses to the commonwealth. The partnership has been urging the Northern Virginia jurisdictions to form a regional group similar to 16 others in the state.

“We’re always at the same site selection shows and marketing to the same people,” said Christina Winn, executive director of the Prince William County Department of Economic Development. “If we’re doing that with one collective voice, that is going to be heard loud and clear.”

[Maryland’s Amazon loss prompts questions about its competitiveness.]

The 14-month effort to land Amazon HQ2 led directly to creation of the alliance. Four Northern Virginia jurisdictions — Arlington, Fairfax and Loudoun counties and the city of Alexandria — combined on a bid offering four separate sites.

It quickly became clear that the online retail giant welcomed the regional approach. That was partly because the company was evaluating not just individual jurisdictions but entire metropolitan regions regarding workforce, transportation and lifestyle.

(Amazon founder and chief executive Jeff Bezos owns The Washington Post.)

“Amazon has point-blank said one of the strongest pieces of our proposal was our collaboration,” said Stephanie Landrum, president of the Alexandria Economic Development Partnership.

She said it will be easier to market Alexandria as part of a larger region.

“In the past, I would pitch to a company and say, ‘You can open your office here and have a beautiful townhouse in Old Town.’ Now I can say, ‘You can open your office in Old Town, and your employees can have a cool horse farm in Fauquier,’ ” Landrum said.

“For the first 10 years of my career, we pitched Northern Virginia as a suburb of D.C.,” she continued. “Over the last two years, Northern Virginia is really emerging as its own identifiable brand. Obviously, Amazon really helped us do that.”

Victor Hoskins, president of the Fairfax County Economic Development Authority, said the change was necessary to compete effectively against national rivals.

“If you go in and all of your little jurisdictions are fighting for attention, and Silicon Valley is competing as one valley, and Boston-Cambridge is competing as one market, you look like you’re very tiny,” Hoskins said. “We have to take advantage of the entire [regional] workforce, the entire portfolio of housing, the entire transportation system.”

Hoskins recently moved to the Fairfax job from the top job in Arlington, where he was in charge during the Amazon effort. Winn, now at Prince William, also recently changed jobs after playing a leading role in Arlington on the Amazon project.

[After helping Arlington land Amazon, Victor Hoskins to become Fairfax County’s economic development chief.]

In the past, many political leaders have resisted regional cooperation because they wanted hometown wins for their own jurisdictions that they could trumpet to voters during campaigns. But minds changed after collaboration worked with the Amazon bid and in winning dedicated funding for Metro.

“It was kind of like a political door opened for us,” Hoskins said. “The electeds said, ‘Hey, we should be doing this. This is how we should work.’ ”

A long-term question for the Washington region is whether the Northern Virginia agreement could eventually be expanded to include the District and suburban Maryland.

Despite progress toward regionwide cooperation, there’s a long history of competition among the two states and the District.

Hoskins portrayed the Northern Virginia alliance as a first step toward a broader project.

“Eventually, we’ll all come together as one region,” Hoskins said. “That’s where we’re trending. But right now, it’s pretty cool to have us 10 working together in Northern Virginia.”