In 1900, the Mack brothers of New York opened a bus manufacturing plant. They had previously built horse-drawn carriages and wagons, then moved to steam- and electric-powered motor cars.
Their first "motorized wagon" was a 20-passenger, 40-horsepower bus. The development of buses meant public transportation could offer flexible routes without expensive street modifications.
Communities throughout Maine added buses -- often privately operated -- to their transportation systems, even as trolleys continued.