It your interested in the Presidential declaration when the day became official, then read below, otherwusexskip this answer.
2008 PRESIDENTIAL PROCLAMATION
President George Bush today signed on April 4th 2008 a Presidential Proclamation making April 6th National Tartan Day! Proclamation signed by the President of the United States:
Americans of Scottish descent have made enduring contributions to our Nation with their hard work, faith, and values. On National Tartan Day, we celebrate the spirit and character of Scottish Americans and recognize their many contributions to our culture and our way of life.
Scotland and the United States have long shared ties of family and friendship, and many of our country’s most cherished customs and ideals first grew to maturity on Scotland’s soil. The Declaration of Arbroath, the Scottish Declaration of Independence signed in 1320, embodied the Scots’ strong dedication to liberty, and the Scots brought that tradition of freedom with them to the New World. Sons and daughters of many Scottish clans were among the first immigrants to settle in America, and their determination and optimism helped build our Nation’s character. Several of our Founding Fathers were of Scottish descent, as have been many Presidents and Justices of the United States Supreme Court. Many Scottish Americans, such as Andrew Carnegie, were great philanthropists, founding and supporting numerous scientific, educational, and civic institutions. From the evocative sounds of the bagpipes to the great sport of golf, the Scots have also left an indelible mark on American culture.
National Tartan Day is an opportunity to celebrate all Americans who claim Scottish ancestry, and we are especially grateful for the service in our Armed Forces of Scottish Americans who have answered the call to protect our Nation.
NOW, THEREFORE, I, GEORGE W. BUSH, President of the United States of America, by virtue of the authority vested in me by the Constitution and laws of the United States, do hereby proclaim April 6, 2008, as National Tartan Day. I call upon all Americans to observe this day by celebrating the continued friendship between the people of Scotland and the United States and by recognizing the contributions of Scottish Americans to our Nation.
IN WITNESS WHEREOF, I have hereunto set my hand this fourth day of April, in the year of our Lord two thousand eight, and of the Independence of the United States of America the two hundred and thirty-second.
GEORGE W. BUSH