Second Monday in October
Festivities are most popular in the Northeast
U.S. celebrates the anniversary of the arrival of the Italian explorer Christopher Columbus to the Americas. Since Columbus Day is a federal holiday, government offices and financial markets are closed, but it is not widely celebrated throughout the US.
Festivities are most popular in the Northeast, particularly in New York and New England.
September – October
Chicago, St Louis, Los Angeles, New Orleans, etc
Oktoberfest season starts in September because its final day typically has a fixed spot on the calendar. The event has been celebrated in Germany—and especially in Bavaria—since 1810, when what started as prenuptial festivities for a royal wedding turned out to be so popular that the local folks decided to recreate the joy the following year.
The traditional October 31 Halloween celebration is much beloved by children in the United States, for whom the day is a chance to don costumes often depicting ghosts, goblins and other supernatural creatures and to collect candy and other treats from adults.