Did Lewis and Clark achieve their goals? What were the lasting effects of their work?

The goals of the Lewis and Clark expedition were to explore and map the new territory gained by the United States with the Louisiana Purchase, establish ties with the native peoples of the region, and catalog the plants and animals there. In all three respects, the expedition can be considered a success.
The Lewis and Clark expedition produced some 140 maps of the region between the Mississippi River and the Pacific Northwest. They accurately charted the course of the Missouri and Columbia Rivers as well as a significant portion of the Rocky Mountains. They found and mapped a reasonable route to the Pacific Coast. All this information was unknown to Americans previously. As a result, Americans could now begin confidently moving into the territory to establish their own presence before other European powers could.
Most of the encounters that the expedition had with Native Americans were peaceful. They encountered many different tribes that provided them with assistance and provisions throughout their journey. While relations between the United States and many of these tribes would, to put it mildly, become strained in future generations, these early encounters did much to foster goodwill. Trade agreements were established with some of these tribes as well. Much was learned about these peoples through the expedition. Lewis and Clark returned with many Native American artifacts, such as bows and cloth, that they had traded for.
Lewis and Clark brought with them a number of books with blank pages. They used these to record their observations of many plants and animals that were previously unknown to Europeans. They also returned with a number of unknown animal pelts, plant samples, and seeds.
As a result of the Lewis and Clark expedition, the United States had a decent idea of what the territory included. They had solidified American claims to the land. They had found a route to the Pacific that other travelers could use. They established trading ties with Native Americans and had cataloged many new species of flora and fauna. Perhaps most importantly, Lewis and Clark brought back information that sparked the imagination of many Americans in the east, who then chose to explore and settle the land themselves.
https://oregonencyclopedia.org/articles/lewis_and_clark_expedition/