Americans are middle endians. They write the date as month/day/year. For example, the fourth day in January would be written like this:
January 4, 2005
1/4/05
01/04/2005
In formal U.S. writings, you never want to omit the year or use a purely numerical form for the date. For example, if you were to write a formal business letter, you'd write out the entire date, including the full month (January 4, 2005). Writing it out in such a way allows the notation to be understood by everyone.