NEW YORK—All was quiet along the Canyon of Heroes on Wednesday morning—or, at least, as quiet as a stretch of downtown Manhattan can be on a summer workday. Flocks of tourists maneuvered around lumbering delivery trucks, hawked to by distributors of seemingly unlicensed 2026 Knicks championship gear. On Broadway, someone watered the flower pots wrapped around light posts.

The forecast for Thursday calls for craziness. Officials are expecting millions of people to descend on Lower Manhattan for what will be one of the largest public events in recent city history as the New York Knicks celebrate their first championship in 53 years with a parade along the same route that has hosted U.S. presidents, military veterans, Olympians and pandemic health workers.

While most major sports teams now commemorate titles with boozy processions, no route matches the historical significance of New York’s Battery Park to City Hall stretch, with roots dating back to the Revolutionary War.

Not long after the 19th century invention of ticker tape, used to track stock prices in real time, employees discovered that throwing the thin rolls of paper out of newly constructed skyscrapers near Wall Street had a similar effect to the flower petals tossed at ceremonies put on for ancient Roman heroes. The first athletes feted along Broadway were members of the 1924 U.S. Olympic team, according to the nonprofit Alliance for Downtown New York.