Richard J. Davidson, longtime president of the Maryland Hospital Association, has been selected as the new president of the American Hospital Association.

C. Thomas Smith, chairman of the AHA board of trustees, announced the board's decision after a six-month national search yesterday.

"Dick Davidson is widely acknowledged as an exceptionally strong, effective leader, and a person who is committed to the public service mission of hospitals," Mr. Smith said.

During his 22 years as president of the Maryland Hospital Association, Mr. Davidson has guided Maryland hospitals through the development of a state hospital rate-setting system and assorted other changes in how hospitals serve their communities.

He became a popular speaker locally, at AHA-sponsored national programs and at colleges and universities across the nation.

Mr. Davidson, who is married and has three sons, holds a doctorate in education from George Washington University.

He was a Ford Foundation research fellow in urban affairs at the University of Delaware.

He has been active in the AHA for 25 years, working on various committees and panels.

Mr. Davidson, 54, will join the Chicago-based not-for-profit association, which serves as a national advocate for hospitals, July 15.

L He will replace Carol M. McCarthy, who resigned in November.