WE JUST KNEW that if Fairfax County had all sorts of jobs going begging -- and the District had so many people out of work and eager not to be -- something good could happen if only another kind of bridge were built across the Potomac. The subject is basic supply and demand here -- with a dash of creativity and enough wheels to get workers to the work. That's why we contacted Mayor Barry, Fairfax Board of Supervisors Chairman John F. Herrity, various Northern Virginia employers and the Greater Washington Board of Trade last month after reporter Barbara Carton's account of these disparities. And good things are starting to happen.

Mayor Barry has responded with enthusiasm, good ideas and resources to make it stick. He has announced a solid proposal to link District workers with Fairfax jobs -- and it's impressively direct and doable. Some of it is obvious but nonetheless important; better information and referral services between the city and the county, for example, are essential. But beyond communications and cooperation are two barriers that Mayor Barry and Chairman Herrity both seek to address: 1) transportation difficulties, and 2) apprehensions about sectional and racial attitudes in the two jurisdictions. Here's what Mayor Barry's plan includes:

There will be a Transportation Response Center, with a hot line to tell individuals on a case-by-case basis how they can get from their homes to particular jobs in the suburbs on existing transportation. This center also will coordinate car pools to jobs. When a suburban employer hires at least five District residents, the city will provide vans or cars to get the employees from certain central locations (Metro stops, for example) out to work sites and back.

When people can reach jobs by subway or bus but cannot meet the cost of fares, the city will subsidize the transit costs, perhaps picking up the difference between the minimum roundtrip fare and the charge for getting to and from the suburbs.

Mayor Barry says he and other officials will meet with suburban employers to match specific jobs and workers and to "customize" training.

Mr. Herrity says Fairfax will welcome trained D.C. workers and will assist the project with administrative services and coordination.

Simple -- and workable. And no doubt these moves will turn up still other steps that might be taken to expand the idea into a broader regional job market with up-to-the-minute data and approaches for delivering workers to work throughout Greater Washington. As we've noted, the District and Fairfax can show the way.