Erickson was raised in Ferndale, Washington, miles ( km) north of Seattle, and in Everett, miles ( km) north of Seattle. His father, Robert "Pink" Erickson, was the head football coach at Ferndale High School before becoming the head coach at Cascade High School in Everett. The younger Erickson played quarterback at the rival Everett High, coached by next-door neighbor, Bill Dunn. This "made for some quiet dinners on game day." As a junior, Dennis was the starting quarterback, beating out the former starter, senior Mike Price, another future college head coach.