The use of hard hats for construction workers started in 1931 at the Hoover Dam site in Nevada.



Typical hat colors are:

white	supervision, architects, supervising engineers
yellow	construction workers
green	first aid, safety or emergency team
blue	direct employees, or emergency team
orange	contractors

Often used in Germany:

white	supervision, architects, supervising engineers
red	foreman, head-workman, site foreman
orange	workers for enforced concrete, steel rod
yellow	construction workers, masons
green	carpenters, timbermans, ring builders, some times security personnel
blue	some times craftsmen, handcrafter