Why did Jefferson fail to send a ship to meet them?
There was no plan to send a ship (what date would they plan to meet?J) The explorers hoped to replenish their depleted trade goods by meeting one of many trade ships that did business with the American Indians at the mouth of the Columbia (Lewis had a letter of credit from President Jefferson). The trade ships avoided the area during the winter, though, because of the dangerous storms and the treacherous Columbia River Bar (sandbars). It turns out that the explorers just missed the first ship of the spring (an American brig: the Lydia) as they began their return trip up the Columbia.