Much of the nation's infrastructure was built on the proverbial
back of the US Army Corps of Engineers (USACE). In the 19th and
20th centuries, it built coastal fortifications, improved harbors,
eliminated navigation hazards on key rivers, surveyed roads and
canals, protected natural resources, constructed buildings and
monuments, and explored and mapped much of the western frontier.
Today, the USACE is the world's largest public engineering, design,
and construction management agency and is involved in research
and development, military contingencies, humanitarian assistance,
environmental protection, and water resource development. The USACE
employs some 37,000 civilians and about 550 soldiers.