The Rockefeller Christmas tree usually goes up in mid November. The tree is usually lit for the first time on the first Wednesday after Thanksgiving. In 2013, that was Wednesday, December 4, and in 2014, that falls on Wednesday, December 3.
When the Christmas tree arrives in Rockefeller Center in November, a crane is used to hoist it into place. Once it is up and secured, workers on scaffolding decorate it with over 30,000 lights. Thousands of people come to watch the initial lighting ceremony, which usually occurs between seven p.m. and nine p.m. and includes live musical performances. The tree stays up and lit through early January.