In 1972, Lightfoot contracted Bell's palsy, a condition that left his face partially paralyzed for a time. The affliction curtailed his touring schedule but Lightfoot nevertheless continued to deliver major hits: in June 1974 his classic single "Sundown" from the album "Sundown" went to No.1 on the American and Canadian charts. It would be his only number one hit in the United States. He performed it twice on NBC's "The Midnight Special" series. "Carefree Highway" (about Arizona State Route 74 in Phoenix, Arizona) was the follow-up single from the same album. It charted in the Top 10 in both countries. Lightfoot wrote it after traveling from Flagstaff, Arizona on Interstate 17 to Phoenix.