Why were red, white, and blue chosen...

The Continental Congress left no record as to why it chose these colors. However, in 1782 the Congress of the Articles of Confederation chose the colors for the Great Seal of the United States with these meanings: white for purity and innocence; red for valor and hardiness; and blue for vigilance, perseverance, and justice. According to the End of the Oregon Trail Interpretive Center (which recently hosted an exhibition on the flag), the colors originated with the British flag, which is a combination of the Scottish cross of St. Andrew (white on blue) and the English cross of St. George (red on white).