Beer and St. Patrick's Day

St. Patrick's day in Boston means

• a huge parade on the Sunday before the 17th (according to Wikipedia, the world's first St. Patrick's Day parade was held in Boston in 1761)
• Corned beef and cabbage
• many people wearing green (or at least a glittering shamrock sticker on a cheek)
• bunches of green and white carnations
• many more Celtics shirts, caps and wristbands to be seen on the streets than usual
• pubs that open at 6 am (for breakfast with beer?)
• Irish music everywhere (where do all the Irish music playing bands come from?)
  
• long lines in front of pubs despite cover charges of up to $ 20 per person ( plus $ 5/glass of beer)
• and people in the road, who are celebrating the Irish saint with heavy alcohol consumption.

What leads to my question: How became getting drunk a St. Patrick's day "tradition"?