Which american artist was a pioneer of abstract expressionism

Jackson Pollock

Explanation:

Jackson Pollock, in full Paul Jackson Pollock, (born January 28, 1912, Cody, Wyoming, U. S.-died August 11, 1956, East Hampton, New York), American painter who was a leading exponent of Abstract Expressionism, an art movement characterized by the free-associative gestures in paint sometimes referred to as "action painting." During his lifetime he received widespread publicity and serious recognition for the radical poured, or "drip," technique he used to create his major works.