The United States Army Corps of Engineers was a military-civilian agency of the government of the United States of America, established in the 18th century and responsible for numerous public works and infrastructure projects both in the United States and others nations of the Earth.
The Corps of Engineers constructed an extensive system of underground maintenance culverts in the Presidio of San Francisco when it was a United States Army fort, for use in case of siege. The tunnels survived the 1906 San Francisco Earthquake and another earthquake in 2182. In 2255, in the alternate reality created by Nero's temporal incursion, Cadet James T. Kirk was led through the Presidio maintenance culverts and into San Francisco National Cemetery by the Gemini Project neural agent with which T'Laya had infected him. (TOS - Starfleet Academy novel: The Gemini Agent)
From 1958 to 1961, Dr. Angela Franklin worked for the Corps of Engineers in Korea, assisting the post-war rebuilding efforts there. (TOS - Star Trek: Assignment: Earth comic: "Brighter Than a Thousand Suns")
- The US Army Corps of Engineers served, in part, as a basis for the Starfleet Corps of Engineers.