St. Patrick's Day parades across the U.S. are planned for Saturday, promising to turn one river green in the Midwest, commemorate the bicentennial of a parade in the South and put forth the first female leader of a major beer company as its marshal.

The holiday commemorates Ireland's patron saint and was popularized by largely Catholic Irish immigrants. While St. Patrick's Day falls on March 17, it's being observed with major parades a day early so it doesn't land on Sunday, a day of rest for the faithful.

In New York City, neighborhoods have held smaller parades for the past few weeks. In February, conservative Staten Island held its first St. Patrick's Day parade allowing LGBTQ+ flags and groups. The main parade, in Manhattan, has included those groups and symbols since 2014.

On Saturday, Heineken CEO Maggie Timoney plans to serve as grand marshal of the Manhattan parade, according to organizers. Originally from Ireland, she is the first female CEO of a major beer company. Some 2 million people are expected to watch.

The Chicago Plumbers Union plans to once again turn the Chicago River green. Organizers say the tradition, started by the union, uses an environmentally friendly powder once used to check pipes for leaks.

In Savannah, Georgia, organizers expect a historic crowd to participate in the parade, which started in 1824. Ahead of the bicentennial, Georgia's oldest city had early 18,000 hotel rooms nearly sold out for the weekend.