Before the Corps of Discovery set off, President Jefferson gave Meriwether Lewis the most generous expense allowance in American history (aside from Major League Baseball's per diem): a letter of credit backed by the U.S. government that allowed him to purchase anything he needed along the route.
The expedition loaded its keel boat with several tons of supplies, including 18 kegs of whiskey, 600 pounds of grease, 226 pounds of gunpowder and 193 pounds of potable soup (which they hated). They also carried beads, blankets, shirts, cloth, tobacco and alcohol to give as presents to the Native Americans.
I am not quite so heavily stocked. I have two suitcases in the trunk of my rental car; an abridged version of the Lewis and Clark Journals; a well-read copy of Dayton Duncan's superb 1987 travelogue of the trail, "Out West;'' an audio version of Stephen Ambrose's "Undaunted Courage;'' two Lewis and Clark guidebooks; a road atlas; an ice chest of diet Pepsi; two Lewis and Clark pewter figurines for the dashboard; and an ever-growing bag of souvenir t-shirts.
I don't have a letter of credit from the U.S. government. But I do have a Visa card with a $25,000 spending limit.