Las posadas

Las Posadas is a nine-days celebration with origins in Spain, now celebrated chiefly in Mexico, and portions of the Southwestern United States, beginning December 16 and ending December 24.

Posada is Spanish for "lodging", or "accommodation"; it is said in plural because it is celebrated more than one day in that period. The nine-day, novena represents the nine months of pregnancy, specifically the pregnancy of Mary carrying Jesus.

But in different places people celebrates them different, check this examples:

In Puerto Vallarta, Jalisco the Vallarta Botanical Gardens hosts a Las Posadas celebration on December 20. During workshops in the daytime, participants make their own nativity scenes with local natural materials including Spanish moss. In the evening, carolers proceed to nativities that are placed among important plants including poinsettias and native Mexican pines. A bonfire and more singing rounds out the celebrations.

· In Wisconsin, the procession may occur within a home, rather than outside, because of the weather.

· An event in Portland, Oregon terminates with Santa Claus and donated Christmas gifts for needy children.

· In New York, worshippers may drink  Atole, a corn-sugar drink traditional during Christmas.

· A large procession occurs along the San Antonio River Walk and has been held since 1966