Slate argues that the famous Lewis and Clark expedition was irrelevant, because they never found a northwest (water) passage to the Pacific, few people read their accounts, and most later explorers found better routes to the west. Interesting article, but I don't buy its claim that Lewis and Clark's fame is a just a result of an ill-deserved PR campaign in the late 1960s. When it comes to discovering new information, often just knowing that something is possible is the most valuable thing. Lewis and Clark proved that it was possible to traverse what became the western US. Sure, with the confidence that it could be done, others followed and found different paths. But somebody had to figure out that it could be done.