He did not reach Lake Itasca; but he did explore the Leech Lake drainage system, which he mistook for the true source.
Hoists the American Flag.
At the British trading-posts, strong log structures fitted to repel Indian attacks, Pike was well received.

Where he found the British flag flying he had it hauled down and the American flag hoisted in its place, making both the Indians and the traders understand that the authority of the United States was supreme in the land.

In the spring he floated down stream and reached St.Louis on the last day of April, 1806.
Returns to St.Louis and Starts Westward.
In July he was again sent out, this time on a far more dangerous and important trip.

He was to march west to the Rocky Mountains, and explore the country towards the head of the Rio Grande, where the boundary line between Mexico and Louisiana was very vaguely determined.

His party numbered twenty-three all told, including Lieutenant J.B.Wilkinson, a son of the general, and a Dr.J.H.Robinson, whose special business it was to find out everything possible about the Spanish provinces, or, in plain English, to act as a spy.