Kelso sits on the Columbia River in southwest Washington state, just across from Longview and within easy reach of both Portland, Oregon and Mount St. Helens, and a rental car makes the most of a location built around Interstate 5 and river-country scenery. Kelso itself is a practical, unpretentious base rather than a tourist destination in its own right, with rental options available through the small local airfield or, more commonly, by picking up in nearby Portland and driving north, a straightforward hour or so along I-5, with most visitors treating Kelso as a quiet overnight stop rather than a long-term base.
From Kelso, Mount St. Helens is the standout draw: the Mount St. Helens National Volcanic Monument and its visitor centers are reached via State Route 504, a well-signed route climbing east from I-5 that takes roughly an hour to ninety minutes depending on how far up toward the volcano's blast zone you go. Portland International Airport lies about an hour south down I-5, making it a common arrival point for visitors who then rent locally and drive north into Washington. The Columbia River itself defines much of the geography here, with river-adjacent roads and small towns like Longview sitting just across the water from Kelso.
Driving is on the right throughout the United States, and this stretch of I-5 is a fast, well-maintained interstate with no tolls, though traffic can bunch up near the Portland metro area during commuting hours. State Route 504 toward Mount St. Helens is a well-paved mountain approach road, generally clear in summer but subject to closures or snow at higher elevations during winter months, so checking conditions before a visitor-center drive between roughly November and April is worthwhile. Fuel stations cluster along I-5 in Kelso and Longview, making refueling easy before heading toward the volcano or continuing north through the Pacific Northwest.