The following verbiage is taken from the Monorail website (link below) to describe its significance:
Seattle Center Monorail was built for the 1962 Seattle World’s Fair to provide a crucial link between the fairgrounds and the amenities downtown.
Construction began in April of 1961 by Alweg Rapid Transit Systems, who received the bid when it offered to underwrite the entire cost of construction.
The Monorail opened to the public on March 24, 1962 nearly one month before the start of the World’s Fair. At a cost of $3.5 million, the trains carried more than eight million guests during the six months of the fair, easily paying for the cost of construction. The full initial capitol cost of the system was recovered and a profit was realized by ALWEG before the end of the fair.
Following the Fair, the Monorail system was turned over to Century 21 Corporation at no cost. Century 21 sold the system to the City of Seattle in 1965 for $600,000.
Today, the trains carry approximately two million passengers every year. The Monorail has become an important fixture in Seattle for locals, who use the trains during major festivals and sporting events. Seattle Center Monorail is one of the few fully self-sufficient public rail transit system in the nation.