It's been two centuries since Meriwether Lewis and William Clark made their historic trek West. In fact, 200 years ago to the day, the expedition was in southwestern Montana, seeking – with the help of the fabled Sacagawea – help from area Indian tribes. I got that fact from the Web site www.pbs.org/lewisandclark, which has about as much information about the expedition as you could possibly want. But … if you want more, then you might consider attending the "Meet the Authors" series that will be held at 7 p.m. Thursday and Aug. 17 in River Park Square. Jack Nisbet, author of the forthcoming book "The Mapmaker's Eye: David Thompson on the Columbia Plateau," will be Thursday's first featured speaker. His talk is titled "Visualizing Rivers: How the Plateau Tribes Introduced David Thompson to the Major Drainages of the Inland Northwest." He will be followed by Robert Carriker, professor of history at Gonzaga University and author of several books, including "The Natural History of the Lewis and Clark Expedition," who will deliver a talk titled "Sergeant John Ordway's Mysterious Salmon River."