Grandma's Marathon - Duluth, Inc. Grandma's Marathon - Duluth, Inc. Search | Advanced Search | New Members | Coupons and Discounts | All Categories Other >> Non-Profit Grandma's Marathon - Duluth, Inc. PO Box 16234Duluth, MN 55816 (218) 727-0947 | fax: (218) 727-7932 Visit Site Send a message to: Grandma's Marathon - Duluth, Inc. Your Name: Your Email: Subject: Message: (Date: 9/21/2019)