Frederick A. Babson Jr., 69, a Northern Virginia lawyer and real estate developer who in 1968 became the first elected chairman of the Fairfax County Board of Supervisors, died Sept. 17 at Arlington Hospital. He died as a result of complications from brain surgery he had undergone Sept. 11 at Johns Hopkins Hospital.

Mr. Babson served six years on the Fairfax Board of Supervisors during the 1960s, but he resigned abruptly in 1969 after less than two years as the board's first elected chairman. He said he was unable to earn a living as a part-time lawyer and part-time chairman of the Board of Supervisors, a position that paid $10,000 a year at the time.

In this period, Mr. Babson also was chairman of the Washington Metropolitan Transit Authority, and in this role, he lobbied aggressively for full federal funding of the Metrorail system, warning that delays would have dire consequences.

"The whole [Metro] project has taken two decades of active work to assemble," he told a joint House and Senate District Committee hearing in 1969. "If Congress does not approve it this year, it will fall apart, and it will take two more decades to restore it to this posture." Later in 1969, Mr. Babson participated in the groundbreaking ceremonies for Metro construction with then-D.C. Mayor Walter E. Washington.

First elected to the Fairfax Board of Supervisors in 1963, Mr. Babson served during a period when the county's population increased dramatically. Land-use policies, the environment, transportation, planning and zoning were critical issues in this period as Fairfax County was being transformed from a collection of rural communities to a bedroom suburb and later to a large metropolitan county.

A resident of Fairfax, Mr. Babson was born in Savannah, Ga., and grew up in Wilmington, N.C. He served in the Air Force during the Korean War, then attended Xavier University and graduated from the University of North Carolina, where he also received a law degree.

He moved to the Washington area in 1958 to work with the Washington law firm of Turney & Turney, from which he later took a leave of absence to represent Fairfax County in an annexation lawsuit against Falls Church. He was president of the Fairfax County Young Democrats and in 1963 won his first term on the Fairfax Board of Supervisors, unseating Republican Robert C. Cotten Jr. in what now is the Annandale district.

During his first term on the board, the chairmanship was rotated among members from the county's magisterial districts. In 1967, for the first time, the position of permanent chairman elected from the county at large was created, based in part on the idea that such a position could meet the leadership needs of a rapidly growing political jurisdiction such as Fairfax.

Mr. Babson defeated Republican Stanford E. Parris for the position, campaigning on the theme of "A Man for All Seasons," to counter his opponent's slogan of "Paris in the Fall."

But the Virginia legislature had seen to it that the chairmanship of the Fairfax supervisors remain a part-time job with little of the authority that strong executives in other jurisdictions enjoyed, and Mr. Babson was unable to assert a sense of leadership in the position. He complained privately of boredom and frustration in the office, which he had been warned might turn out to be a "half a loaf" proposition. In November 1969 he resigned.

Mr. Babson also was a former chairman of the Metropolitan Washington Council of Governments, and he was president of the National Organization of Councils of Governments. He was chairman of the Northern Virginia Transportation Commission and a member of the Virginia Democratic Central Committee, the Washington Board of Trade and the executive committee of the Virginia Association of Counties.

After leaving the Fairfax Board of Supervisors, Mr. Babson practiced law and developed office building projects in Northern Virginia and a resort condominium project in Virginia Beach. In the late 1970s, he was one of seven Democratic contenders for the U.S. Senate nomination to run against John W. Warner.

His avocations included golf.

His marriage to Joan Babson was annulled, and his marriages to Joanne Staupe and Patricia J. Carroll ended in divorce.

Survivors include a daughter from his marriage to Joan Babson, Jo Michelle Tang of Washington state; two sons from his marriage to Joanne Staupe, Michael Babson of Manassas and Christopher Babson of Los Angeles; and three children from his marriage to Patricia Carroll, Jennifer Babson of Miami, Frederick A. Babson III of Chicago and Katherine Babson of Arlington; a brother; and three grandchildren.