Led by a renowned Mexican poet, a four-mile march through Chicago’s West Side on Monday evening called for an end to the U.S. war on drugs. Javier Sicilia, whose 24-year-old son was killed last year by Mexican drug traffickers in Cuernavaca, blames the drug war for tens of thousands of violent deaths in that country.

Sicilia says the war has been devastating north of the border too. To make that point, he is leading a month-long bus caravan through the United States. His group joined hundreds of Chicago activists on the march, which began in the city’s Little Village neighborhood and ended in West Garfield Park.

“These are African-Americans and Latinos who have been criminalized,” he told WBEZ in Spanish, motioning to bystanders watching the march. “They are more vulnerable because there is a drug war.”

Sicilia said the war on drugs, which dates back to President Richard Nixon’s administration, has fueled mass incarceration and street violence in the United States.

He compared that bloodshed to Chicago gangster violence during Prohibition almost a century ago. But the drug war has deeper effects, Sicilia said, “because the scale is international and the weaponry is more powerful.”

Sicilia said authorities should treat drug use as an issue of public health, not criminality.

The caravan is scheduled to wrap up in Washington next week.