Instagram/Sara Landry & Green Velve Music ARC Music Festival expands to 4 days in 2026 at Chicago's Union Park. See the new lineup and experience an extended Labor Day Weekend of electronic music. March 22, 2026 AceShowbiz - The ARC Music Festival in Chicago is set to grow in 2026, extending its run from three days to four during Labor Day Weekend, September 4-7. The festival will once again take place at Union Park, solidifying its status as a landmark event in the city's vibrant music scene.