Joseph E. Blackburn, Chesapeake & Potomac Telephone Cos. vice president for regulatory and public affairs, will become the firm's chief officer in Virginia with responsibility for statewide telephone service, C&P said last week.

Blackburn succeeds Lee C. Tait, who has served as vice president and director of the Virginia company since 1970. Tait will retire in January 1984, and Blackburn will assume his position then.

Pending Tait's retirement, Blackburn will become vice president and a director of C&P of Virginia on Aug. 1 and will report to Tait, who has been elected senior vice president. Tait will remain a director of the company after his retirement.

Blackburn joined C&P in 1957 as an attorney in Richmond. He moved to C&P group headquarters in Washington in 1974 as vice president for revenues before being named to his present position in 1981. He will be headquartered in Richmond with his new position.

He was a member of the Virginia State House of Delegates from Lynchburg from 1954 to 1958.

C&P operates companies in Washington, Maryland, Virginia and West Virginia. Each area is managed by a company vice president who reports to Thomas E. Gibbons, president and chief executive officer of C&P Telephone Cos.