The Continental Congress encouraged the use of stagecoaches to transport mail.
The use of stagecoaches to transport mail stimulated the growth of stagecoach lines.
As the railroad expanded, railroad lines were designated as postal routes.
Mail was sorted by route agents at many railroad stations.
Scheduled airmail began providing service in 1918. Pilots flew without navigation instruments.
In cities where postage income would cover the cost, free delivery was provided to residents.
City delivery required that Americans use street addresses on their letters for the first time.
The above were the Lord & Taylor 2004 windows along Fifty Avenue, New York City.
This link will give you more history about Lord & Taylor windows: http://www.prnewswire.com/news-releases/deliver-the-joy-lord–taylor-holiday-windows-to-unveil-history-of-delivery-and-us-postal-service-holiday-ornaments-stamps-75375762.html (To view, copy and paste the link in your browser)
Read some about Christmas:
The celebratory customs associated in various countries with Christmas have a mix of pre-Christian, Christian, and secular themes and origins. Popular modern customs of the holiday include gift giving, Christmas music and caroling, an exchange of Christmas cards, church celebrations, a special meal, and the display of various Christmas decorations, including Christmas trees, Christmas lights, nativity scenes, garlands, wreaths, mistletoe, and holly. In addition, several closely related and often interchangeable figures, known as Santa Claus, Father Christmas, Saint Nicholas, and Christkind, are associated with bringing gifts to children during the Christmas season and have their own body of traditions and lore. Because gift-giving and many other aspects of the Christmas festival involve heightened economic activity among both Christians and non-Christians, the holiday has become a significant event and a key sales period for retailers and businesses. The economic impact of Christmas is a factor that has grown steadily over the past few centuries in many regions of the world.