Rescue archaeology was a movement of the early 1970s, particularly in Britain which sought to lobby to help stop the loss of archaeological evidence, where it was threatened by building development work in the historic cities, and by agriculture. It is called Salvage archaeology in the United States.
The focus of early work was in setting up organisations that could undertake 'rescue' excavations in the teeth of the bulldozer. Archaeologists relied on the goodwill of the developer to provide the opportunity to record remains, and work was poorly funded through a mixture of government grants and donations. As a result, excavations were hurried and often unstructured. Later on the need to conserve archaeology in the ground has become more apparent.
In UK it has now been largely superseded by archaeology's incorporation into the planning process through the introduction of PPG 16 in 1990.