Final answer:
Electric trolleys in Boston began use soon after their invention by Frank Sprague in 1887. Boston's L-trains and the subway system were introduced in 1887 and 1897, respectively, enhancing urban public transport.
Step-by-step explanation:
The use of electric trolleys in Boston began shortly after their invention. In 1887, Frank Sprague introduced the electric trolley, and not long after, Boston followed other cities by adding elevated trolley lines, known as L-trains, to navigate more efficiently through crowded city areas. By getting the trolleys off the streets, it allowed for less traffic and fewer accidents with pedestrians. Progressing with transportation developments, Boston's subway system started operating in 1897, reflecting the technological advancements of the electric age and the changing landscape of urban transportation.