They are 3,000 miles apart, but there are few counties more closely linked by history and similar in many ways than Marin in California and Fairfax in Virginia. Both counties contain an incorporated community named Fairfax, so called for the same landed family that once owned all of Northern Virginia and later had an estate in this place that bears its name.

Charles Snowden Fairfax, who was in hereditary line to become the 10th Lord Fairfax, Baron Cameron, but never claimed the title, sailed to San Francisco from Virginia in 1849. Then 20 years old, he was part of the Virginia Company, a private investment enterprise, whose 75 members came in quest of gold, but went their own ways -- many entering politics or making canny investments in real estate.

Charles Fairfax failed at mining, but soon became speaker of the state Assembly and later clerk of the state Supreme Court. By contemporary accounts, he was something of a dandy, fond of fine clothing, gambling and drink.

He moved to Marin, a county with a location close to San Francisco, comparable to Fairfax County's nearness to Washington. Here, in a steep-sided valley, he and his wife -- who reveled in being called "Lady" Fairfax -- bought a 31-acre stand and erected a home. The nearby railroad station took his name, as ultimately did the town.

After a term on the Marin County Board of Supervisors, he died childless in Baltimore in 1869, at age 40. He had gone east as a delegate to the 1868 Democratic national convention.

In population, Marin's 223,000 population is about one-third that of Virginia's Fairfax County, and, by coincidence, the 7,300 people in this Fairfax make it about one-third as populous as Fairfax City in Virginia.

I spent many idyllic childhood weekends in this Fairfax. Early in my newspaper career, I covered many fractious meetings of the Fairfax Town Council. I'd speculate that I'm the only reporter who has covered meetings of both the Fairfax, Calif. and Fairfax, Va. councils.

Both Fairfaxes are commuter bedroom towns, though this one is more rough-hewn and hillside-rustic than Virginia's. A trip through the small downtown here a few days ago found boutiques mushrooming among the modest shops. But the Corner Bar, where refreshment was to be found after council meetings in the late 1940s, is still there, with an honest drink being dispensed for $1.25.

Marin and Fairfax counties are economically similar, with both in the top five in per capita income among all suburban metropolitan counties in the nation. Census figures in 1981 show Marin as No.3 on that list, with $14,741 per capita, and Fairfax County as No.4, with $13,952. Incidentally, Arlington (with a large number of employed single people) is No.1 with $15,323 and Montgomery County, is No. 2 with $14,969.