Complex sentence: The last surviving commercial common carrier narrow-gauge railroad in the United States is the White Pass and Yukon Route connecting Skagway, Alaska and Whitehorse, Yukon Territory; this closed in 1982, but has since been partially reopened as a tourist railway.
Split into simpler sentences: The last surviving commercial common carrier narrow-gauge railroad in the United States is the White Pass and Yukon Route connecting Skagway, Alaska and Whitehorse, Yukon Territory. It ended common carrier service in 1982, but has since been partially reopened as a tourist railway.