In-N-Out Burger has most of its locations in the western United States, where it began in California. The company has gradually expanded into other states while keeping its focus on fresh ingredients and consistent food quality. Its restaurants are commonly found in busy shopping areas, along major roads, and near residential communities. Unlike many fast-food chains, In-N-Out has expanded relatively slowly, helping it maintain control over its food preparation and customer service.

As of 2026, In-N-Out operates more than 400 restaurants across 10 states: California, Nevada, Arizona, Utah, Texas, Oregon, Colorado, Idaho, Washington, and Tennessee. California has the largest number of locations, while newer expansion has brought the chain farther east to Tennessee. The company also plans to expand into New Mexico. However, In-N-Out does not currently have restaurants in Hawaii, so customers living there would need to travel to a state where the chain operates to try its food.