SAN JUAN, Puerto Rico (AP) _ Pilar Barbosa de Rosario, a prominent Puerto Rican historian who championed statehood for the U.S. commonwealth, has died. She was 99.

Barbosa, who died Wednesday, was for decades considered the conscience of Puerto Rico's governing New Progressive Party.

She wrote more than 20 books, mostly on Puerto Rico's history, received the U.S. Outstanding Leadership Award from President Ronald Reagan in 1984 and was active to the last, being appointed Official Historian of Puerto Rico in June 1993.

Barbosa was the daughter of Jose Celso Barbosa, considered the founder of Puerto Rico's statehood movement.

``The greatest posthumous tribute that our people could render Dona Pilar would be to dedicate themselves to the 1998 plebiscite,'' said Carlos Romero Barcelo, Puerto Rico's delegate to Congress and another advocate of statehood. The proposed ballot would try to determine the future relationship between the United States and Puerto Rico.

Barbosa earned her bachelor's degree in education at the University of Puerto Rico in 1924 and her master's degree in history, international relations and education from Clark University at Worcester, Mass., a year later.

In 1926, she became the first Puerto Rican woman to teach at the University of Puerto Rico and, a year later, established its History and Social Sciences department.

Gov. Pedro Rossello declared three days of national mourning.