In the United States, Christmas was officially recognized as a national federal holiday in 1870, with the official date being December 25. During the Middle Ages, some Christians in Europe started to celebrate the birth of Jesus. Prior to this, the Romans held a winter festival that involved the exchange of gifts and parties.
The Bible does not mention December 25 as the day of Jesus's birth. However, December 25 was the date of the Roman winter solstice and a part of their winter festival.
After the Reformation in the 16th century, Christmas celebrations fell out of favor. Parties and many of the associated activities were considered to be unchristian behavior. Around 1840, it became more common and acceptable to celebrate Christmas again.