Blue not green is the color originally associated with St Patrick. “St Patrick’s Blue” is used on Ireland's Presidential Standard or flag, while the Irish Guards sport a plume of St Patrick’s blue in their bearskins. The emphasis on green is thought to be linked to “wearing the Green”, a symbol from the 18th century on, of sympathy with Irish independence.
The first St Patrick’s Day parade took place in 1737 in Boston, followed in 1762 by New York. George Washington allowed his soldiers a holiday on March 17, 1780 as “an act of solidarity with the Irish in their fight for independence.”
Until the 1970’s, all pubs were shut in Ireland on St Patrick’s Day, and the sole venue selling drink the annual dog show. Lenten fasting – and the obligation to abstain from meat – were lifted on the day, which most families would begin with Mass.
Since 1962, tons of green dye are tipped on St Patrick’s Day into the Chicago river, although the quantity has reduced, for environmental reasons, from 100 to 40.