This paper describes a new method for estimating the fire interval distribution of a region using historical wildfire boundary data. The new estimator does not assume a specific model and is shown to have good statistical properties. In Los Angeles County, California, detailed information on wildfires has been made available through the use of geographic information systems (GIS) technology. The proposed estimator is applied to GIS data covering the years 1878-1996 and reveals an apparent nonlinear threshold-type relationship with burn area.