CHM has its roots in the rescue archaeology and urban archaeology undertaken throughout North America and Europe in the years surrounding World War II and the succeeding decades. Salvage projects were hasty attempts to identify and rescue archaeological remains before they were destroyed to make room for large public-works projects or other construction. In the early days of salvage archaeology, it was nearly unheard-of for a project to be delayed because of the presence of even the most fascinating cultural sites, so it behooved the salvage archaeologists to work as fast as possible. Although many sites were lost, much data was saved for posterity through these salvage efforts.