In 1970 McCall was faced with a potential riot in Portland. In May of that year a week-long student protest at Portland State University over the Kent State shootings had ended with charges of excessive police violence. The American Legion had scheduled a convention in Portland later that summer; local antiwar groups were organizing a series of demonstrations at the same time under the name of the "People's Army Jamboree" and expected to draw up to 50,000 protesters.

After attempts to convince the People's Army Jamboree to either not carry out their plans or to move the date, McCall decided to hold a rock festival at Milo McIver State Park near Estacada, Oregon called "Vortex I: A Biodegradable Festival of Life," in imitation of the famous Woodstock Festival held the previous year.

"I think I just committed political suicide," McCall is reported to have remarked immediately after approving the event. Vortex was the first and so far only state-sponsored rock festival in U.S. history.

The festival, nicknamed "The Governor's Pot Party" by Oregonians, was a success, attracting between 50,000 and 100,000 people. Gold, The Portland Zoo, Osceola, Fox, and Chrome Cyrcus were among the bands that played. The media announced that Santana, Jefferson Airplane, and the Grateful Dead were on the way, but none of them appeared. The feared violent clash between the antiwar groups and the conservative American Legion was avoided, and the city of Portland passed the summer relatively uneventfully. McCall was re-elected in November, with 56% of the vote.