BOSTON -- It began as an idea in Chicago, and morphed into a nationwide movement in 2002. On Wednesday, millions of parents and students across the country hoofed it for Walk To School Day.

The event strives to encourage students to combat pollution and childhood obesity.

Students in communities across Massachusetts ditched the buses and walked to school.

WCVB reported that at the O'Donnell Elementary School in Boston, nearly 80 percent of the students strolled to their studies. The students also participated in a "Walk To School" parade and were joined by students from 30 other communities across the Bay State.

In Halifax, commuters were being warned of possible traffic delays on Route 106 because of the expected increase in walkers.

In Stoneham, an estimated 1,000 parents, students and teachers formed walking groups and used walking maps to get to school.

For parents who couldn't walk their kids all the way to school, it was suggested they walk their children to the bus stop or park farther away from the school.

The Partnership for a Walkable America maintains an online resource for students, parents and communities wishing to get involved. The Web site also offers guides to create safe walking routes with the assistance of the National Center for Safe Routes to School.

October has been declared International Walk To School Month.