EARTH DAY HAS BEEN MARKED ON APRIL 22, EVERY YEAR SINCE 1970. IN THAT YEAR, STUDENTS GATHERED AT COLLEGES AND UNIVERSITIES AROUND THE UNITED STATES TO RAISE AWARENESS OF WIDESPREAD ENVIRONMENTAL DEGRADATION. THIS YOUNG MAN PARTICIPATED IN THE EVENT HELD NEAR PACE UNIVERSITY IN NEW YORK.

THE 1970 EVENT WAS ALSO OBSERVED BY THOUSANDS OF PRIMARY AND SECONDARY SCHOOL STUDENTS. THESE KIDS, FROM THE CHILDREN OF THE SACRED HEART SCHOOL IN NEW YORK, HELPED CLEAN UP A MONUMENT IN THE CITY'S UNION PARK.

CONCEIVED AS A GRASS-ROOTS EVENT, CELEBRATED ON A DAY CHOSEN BECAUSE IT DID NOT CONFLICT WITH HOLIDAYS OR COLLEGE EXAMS, EARTH DAY HAS EVOLVED INTO A HOLIDAY WITH NO PARTICULAR TRADITIONS OR METHODS OF OBSERVANCE.

IN 1990, THESE EARTH DAY PARTICIPANTS ORGANIZED A COLLECTION OF TOXIC HOUSEHOLD WASTE PRODUCTS IN THE PARKING LOT OF OIL GIANT UNOCAL.

THIS FIVE-STORY GLOBE WAS CONSTRUCTED IN WASHINGTON TO MARK THE 25TH ANNIVERSARY OF THE HOLIDAY.

THESE ACTIVISTS CREATED COSTUMES OF WASTED CANS FOR AN EARTH DAY EVENT IN SEOUL IN 1996.

PAUL MCCARTNEY AND RINGO STARR APPEARED AT THIS 1993 LOS ANGELES EARTH DAY CONCERT.

CHILDREN IN KATMANDU, NEPAL TURN OUT FOR THE PLANET IN 2002.

IN THE YEAR 2009 EARTH DAY IN WASHINGTON WILL BE CELEBRATED BY THE FLAMING LIPS, LED BY WAYNE COYNE, ABOVE.