In-N-Out Burger 1261 S Lone Hill Ave, Glendora, CA91740 In-N-Out Burger is located off of Lone Hill Avenue in the Home Depot Plaza. In-N-Out Burger was opened in 1948 by Harry…More and Esther Snyder in Baldwin Park, California. In-N-Out Burger is well known for the delicious hamburgers and fries. It focuses on one thing and has been doing it well for over 60 years. The convenient drive-thru makes service fast, simple and pleasant for customers.