The catastrophic, explosive eruption of Mount St. Helens, Washington, on May 18, 1980, is the most well-known eruption of the volcano. Less well known is that the May 18 eruption marked the beginning of a period of eruptive activity that lasted through 1986. Beginning in October 1980, a series of 17 dome-building episodes added millions of cubic meters of lava to the crater floor. Most of the growth occurred when magma extruded onto the surface of the dome, forming lava flows up to approximately 198 to 396 meters (650 to 1,300 feet) long and 20 to 40 meters (65 to 130 feet) thick. This data release is a 1-meter resolution digital elevation model (DEM) and a corresponding hillshade raster derived from a previously unpublished 1:2,000 scale topographic contour map, based on aerial photographs taken on September 13, 1984, created by USGS for use during the response to the eruption.