The expedition's supplies included an unknown number of American flags resembling the one seen here. Those that the journals refer to only as being "of second size," and "of third size" (at least nineteen of the latter), were given to selected Indian leaders as tokens of peace, and to represent a bond of union between the tribe and the United States of America.
Beginning in the seventeen-seventies, a half-dozen or more flags of different designs and colors were used in the various colonies. The flag of thirteen stars and thirteen stripes, signifying the thirteen original colonies, was authorized by Congress in 1777. The colors, the same as those of the British flag, were chosen at a time when many Colonial leaders still hoped for reconciliation with Great Britain.
Eighteen years later, after Vermont and Kentucky were admitted to the Union, Congress established the format you see here: seven white and eight red stripes, with 15 five-pointed white stars in a blue field.
Congress made no provision for further changes in the flag when new states joined the Union. So the old 15-star flag was still the official one at the time the Lewis and Clark expedition began, although there were actually 17 United States. They were, in order of admittance: Delaware (1787), Pennsylvania (1787), New Jersey (1787), Georgia (1787), Connecticut (1788), Massachusetts (1788), Maryland (1788), South Carolina (1788), New Hampshire (1788), Virginia (1788), New York (1788), North Carolina (1789), Rhode Island (1790), Vermont (1791), Kentucky (1792), Tennessee (1796), and Ohio (1803). The next state to be admitted was Louisiana, in 1812.
The present design was established in the Flag Act of 1818: six white stripes, seven red, and a blue field with one star for each state in the Union.
Now about those other names: The men of the expedition wouldn't have referred to their flag as the "star-spangled banner" because that expression was coined by Francis Scott Key in 1814. Key's poem, set to a tune that had been popular for many decades, officially became our national anthem in 1931.
They wouldn't have called it "Old Glory," either, because that name was given it by a young sea-captain of Salem, Massachusetts, in 1824.
The expedition carried just one large flag, which probably flew above their major camps. We don't know just how big it was, but before they left Fort Clatsop on March 18, 1806, they cut it up to make five "robes," or capes, to trade with Indians for food and horses. That was perfectly legal then. The first law prohibiting desecration or improper use of the flag was passed by Congress in 1917.
Incidentally, the story that Betsy Ross sewed the first Stars and Stripes in 1776 appeared nearly a century later, and doesn't jibe with historical facts.
Bob Saindon, "The Flags of the Lewis and Clark Expedition," We Proceeded On, Vol. 7, No. 4.
Whitney Smith, The Flag Book of the United States. New York: William Morrow & Company, Inc., pp. 66-74. Encarta, 1994.
Milo M.Quaife, Melvin J. Weig, and Roy E. Appleman, The History of the United States Fla. (New York: Harper, 1961.