From Fraternally, Yours by Bernie Lucko:
"This was a relatively small but
diverse labor organization. In 1944, there
were 125,000 members in 435 locals of this
union that was headquartered in Detroit,
Michigan. By that time, the union included
motormen, conductors, guards, brakemen,
trolleymen, bus and coach operators, garage
men and all men operating cars and trams,
all gatemen, watchmen and Wardens, all
employees of the car houses and pit
department, all collectors, janitors,
watchmen, yard crews, elevator men,
porters, clerks, trackmen and laborers. One
has to wonder why there are not more mugs
depicting this trade with so many jobs
included within the union. In addition,
individuals who held minor position such as
starter, dispatcher, inspector, timekeeper,
streetmen or barn shop and track foremen,
"working with their fellow workers and not
having the power of discipline in the way of
hiring, suspending or discharging
employees," (that is, non-supervisors) could
join the union.
The union was organized in 1892 in
Indianapolis, Indiana and initially
represented those working with horse drawn
and electric trolley and interurban rail lines.
These individuals primarily moved
passengers, not freight, and were not directly
connected with the interstate railroads that
crossed the country during this period of
industrial growth.
The mug depicts an electric street car
with the letters "AA of S & ERE of A"
above it."
From
The Historical Society of Pennsylvania:
The Amalgamated Association of Street and Electric Railway Employees of America (Amalgamated) formed in 1892. Arguing for increased benefits and compensation, Amalgamated organized successful, but occasionally violent, strikes of Philadelphia Rapid Transit Company workers in 1909 and 1910. The union continues today as the Amalgamated Transit Union (ATU).