The federal government has stiffed Prince George’s County again, deciding to keep 3,000 good office jobs in Montgomery County despite wide agreement on the need to promote employment in the less-developed eastern half of our region.

It’s the latest illustration of a major, chronic problem afflicting the Washington area. Our biggest employer, Uncle Sam, makes crucial choices about where to locate jobs with little heed to vital regional goals, such as reducing traffic and encouraging balanced economic growth.

Want a second example? Northern Virginia commuters are about to suffer the consequences of an earlier, boneheaded federal decision to move 6,400 Defense Department employees to the Mark Center in Alexandria.

The new site is near no Metro station, so the new arrivals will add to gridlock at the intersection of Interstate 395 and Seminary Road. The ramps there are already classified as providing “failing levels of service” because of congestion.

Moreover, nine out of 10 of those Defense employees previously worked near Metro stations, mostly in Crystal City and the Ballston corridor in Arlington. In making the change, the Pentagon rejected vocal opposition from the state and most local governments.

And while Montgomery succeeded in keeping the large Health and Human Services Department facility in Rockville, it’s bracing for much worse traffic in Bethesda following the Pentagon’s decision to move the Walter Reed medical center there.

Such headaches recur mainly because the federal government functions as a realm unto itself. It focuses on internal criteria that ignore or give short shrift to its neighbors’ best interests.

That’s especially true of the Pentagon. It typically contends that it isn’t responsible for what happens outside its facilities’ gates.

The Mark Center change was decided in 2005 as part of the larger Base Realignment and Closure process. BRAC as a whole is estimated to have moved more than 20,000 jobs in the Washington area farther away from Metro stations. How self-defeating is that?

(As I discussed in a June 2 column, the House passed a bill to allow some BRAC moves to be delayed. The Senate hasn’t acted, and now it’s too late.)

Non-Defense agencies try more to cooperate. That’s partly because President Obama issued an executive order in 2009 calling on the General Services Administration to move jobs near mass transit whenever possible.

But the GSA showed its limitations when it decided last week against moving the 3,000 HHS jobs from Rockville to Largo or two other Prince George’s locations that had bid for them.

In one of the biggest federal leasing deals ever reached in our area, the GSA awarded a 15-year contract for nearly 1 million square feet of office space to renovate the Parklawn Building and keep the jobs in Montgomery.

The GSA saved money with the decision, partly because Montgomery kicked in a more alluring county financial subsidy than Prince George’s was offering. But the region missed an opportunity.

For years, area leaders have been talking up the need to add jobs in Prince George’s. The county has more acres of under-used land, much of it convenient to Metro, than any other jurisdiction. One Prince George’s site lost despite having the advantage of being only 525 feet from the Largo Town Center station, whereas the Montgomery site is 2,407 feet away from the Twinbrook station.

In addition, placing more jobs in the eastern half of the region would help reduce congestion, especially on the Beltway. That’s because a disproportionate number of workers live in the eastern half of the region, but have to commute to jobs in the more prosperous western half.

Prince George’s politicians and business complain that the GSA still views the county as a place for storage facilities and other low-end installations, even though its demographics have improved.

“In the past, Prince George’s County was happy with warehouses. But that’s no longer true, now that we have a highly educated, skilled workforce,” said David Iannucci, a top county economic development official.

Bob Peck, GSA commissioner of public buildings and a former president of the Greater Washington Board of Trade, endorsed the goal of adding jobs in Prince George’s but said the cost was too high this time.

“If we’ve got a brain, we’ll put more government and private development around Metro transit stations in Prince George’s. In this case, the price was a big deal,” Peck said.

The losing effort underlines why the Prince George’s County Council should approve County Executive Rushern L. Baker III’s plan to create a $50 million economic development fund so it can be more competitive. And the GSA and, especially, the Pentagon should pay more mind to improving the quality of life in the region that is home to more federal employees than any other.