Till the turn of the 20th century, Ganesh Chaturthi was celebrated only in homes and temples.
But during the struggle for independence, freedom fighter Lokmanya Tilak started the custom of 'Sarvajanik Ganeshotsav' -- public festival.
Ganesh Chaturthi: The Full Coverage
Tilak thought, rightly so, that a festival like this had the potential to galvanise the public.
There was a political message behind it but the British could do nothing as it was packaged in religion.
Once independence was achieved, the political angle behind the event ceased to exist. But the tradition has carried on.