Steamfitters Local 602 was formed in 1913, through the merger of several earlier locals, and became a part of the United Association of Plumbers, Gas Fitters, Steamfitters and Steamfitters' Helpers of the United States and Canada, which had been founded in 1889.

In the early 1900's, the labor movement was in its infancy, and as in many new ventures, there were problems and conflicts. The construction industry in the Washington area was growing, and it took some time for local labor relations process to mature and stabilize.

Nonetheless, it did happen, and the members of Local 602 began to enjoy increasing wages, labor peace and recognition as the decades passed. Progress was not always straight line, however. There was a recession in 1921-22, following World War I, but this was succeeded by a construction boom in the mid-1920's. The stock market crash of 1929 began the period of the Great Depression of the 1930's, when jobs were scarce in all industries. But Local 602 was in a relatively good position even then. The recovery programs initiated by the Federal Government in the 1930's resulted in the construction of many government buildings, which meant work and wages for the members of Local 602.

World War II followed, which brought much private construction to a standstill, but the '40's were still boom years, as major military installations were built in the Washington area. Following the war, the civilian economy took over and projects for utilities, schools, housing, shopping centers and commercial/industrial buildings kept the construction industry strong.

In 1949, a new idea was put into place: the first Medical Fund, programs which grew into the comprehensive coverage programs union members have today. In 1955, the Pension Fund was activated, and two years later, Apprenticeship and Pension Fund contractor contributions were negotiated with the Mechanical Contractors D.C. Association. In 2001, the Retirement Savings Plan (RSP) was established as the men and women of Local 602 continued to gain more and more benefits from their membership.

In the 1970's developments brought significant changes to the construction industry. The oil crisis, inflation, high interest rates and soaring land values greatly increased the cost of construction, and spawned increased competitiveness and demands for efficiency by the owners of building projects.

At the same time, changes in technology have brought about dramatic expansion within the refrigeration and air conditioning industry. These changes put a premium of quality service of existing systems, and so Local 602 has negotiated collective bargaining agreements that are pertinent to craftsmen and women in the service business and different from other segments of the mechanical trades. This move has led to a significant broadening of the steamfitters' craft.

Today, Local 602 has some 3,300 active journeyman members along with 471 apprentices. These men and women represent the very pinnacle of the trade. Superbly trained, highly motivated and well rewarded for the heavy responsibility they bear and the demanding, highly technical work they perform.