Local 2150 was chartered as a Communications Workers of America (CWA) Local in 1949, but its origins can be traced to the Bell Systems company unions of the 1920s. In 1935, the passage of the Wagner Act the Long Lines employees in Maryland were organized into Long Lines Local 16, a group of the Long Lines American Union. Each of the Long Lines Locals sent a representative to meet with the Bell System's Vice-President of Long Lines concerning their own grievances. The Bell System management was thus able to pit one local against another, and avoid being pressured into making changes beneficial to workers. This prompted the formation of the National Federation of Telephone Workers (NFTW), of which the Baltimore local was a part.

Following the formation of the NFTW, the Baltimore long-lines local was known as Local 16, NFTW. Other groups of telephone workers in the same geographical area had their own locals and barahined separately with their own management. Local 16 was very small, with its officers forced to conduct business out of their homes. The widespread telephone strike of 1947 was an ordeal, a catalyst for growth, and a point of fracture for the union. The local drew up a schedule, and manned the picket lines daily throughout the six-week strike. During the strike, the much larger Chesapeake & Potomac Traffic Division's union invited Local 16 to share its headquarters for a nominal fee, giving the union access to its own office space for the first time. Despite this advance and the settlement of the strike, there was growing dissention within the NFTW.

In the aftermath of the 1947 strike, there evolved two groups. Joe Beirne of the Western Electric Sales Union wanted to form an independent national union, the Communications Workers of America. Jack Moran, president of the New York Long Lines disagreed and sought to join the Congress of Industrial Organizations (CIO), forming the Telephone Workers Organizing Committee (TWOC) -CIO. Local 16 sided with Moran, once again undergoing a change of name to Local 16, TWOC-CIO.

In 1949, the CWA finally joined the CIO. This prompted one final name change for the Baltimore-area long-lines union. The organization was designated Local 2150, CWA-CIO. The numbers represented the district and type of workers the Local represented. The 2 designated the Local's District, 1 indicateded that this was the district's first Long Lines local, and 50 is the union's code for Long Lines employees. Local 2150's charter gave it jurisdiction over all Long Lines offices in the state of Maryland. It represents members from Baltimore, Elkton, Fairlee, Finksburg, Frostburg, Hagerstown, Randallstown, and Waldorf.

The scattering of membership across the state sometimes proved to be a hindrance to representation of members by the union's officers. It was hard for a few officers and staff to effectively address the particular grievances of these far-flung offices and operations. This siruation persisted until the 1960s, when the office of Chief Locality Steward was created. These were to be the highest-ranking union official in each office, dealing directly with the various operations managers. This allowed the Local's president and vice-president to deal with the district managers and the CWA International.

In 1973, Local 2150 became involved in a dispute with CWA Local 2350 over the right to organize workers in Waldorf, MD. The contending locals turned to the international union, which, after reviewing the arguments, ruled in favor of Local 2350. In 2003, after a period of waning membership numbers, Local 2150 was merged with a CWA local based in Virginia.