In the post-apocalypse, folks getting by in the Sanctuary (the remains of St. Louis) are surprised when a woman rushes in to report that in the West, civilization flourishes and crops grow. Unfortunately, there's also an army on the march that enslaves everyone it encounters.

Lewis and Clark: forever paired for their epochal first crossing of the continent in 1804-1806, darlings of the young republic, and the pride of Thomas Jefferson because they made his dream of a nation between two oceans come true.
Lewis and Clark: two great but very different men.
Plain-spoken William Clark, enjoys the triumphs and acclaim of the expedition, marries his childhood sweetheart, and settles in St. Louis as superintendent of

...

After Halley's Comet was destroyed in a magical battle in 1759, the backlash separated the entire New World from the Old in an event known as The Sundering. In America, magic works. It is 1803, and Meriwether Lewis is attending a talk by Benjamin Franklin when it is disrupted by the attack of a winged fire-breathing beast. Franklin tells Lewis of a great, growing evil that lurks in the uncharted Arcane Territories west of the Mississippi, and commissions...

Seaman, Meriwether Lewis's Newfoundland dog, describes Lewis and Clark's expedition, which he accompanied from St. Louis to the Pacific Ocean.