Lincoln Airport (LNK) is a small regional airport about 8 km northwest of downtown, served by American, Delta, and United with connections through their hubs. For more options, Omaha's Eppley Airfield (OMA) is 90 km east on Interstate 80 — a straightforward 50-minute drive — and has significantly more routes.
By road, Lincoln sits directly on Interstate 80, the main transcontinental highway. Denver is five hours west; Omaha is just under an hour east. Greyhound operates bus service connecting Lincoln to Omaha, Denver, and Kansas City. Amtrak's California Zephyr passes through Lincoln with stops at the historic Amtrak station, though the westbound train arrives around 3 a.m. and eastbound around 2 a.m. — not ideal, but the route through the Rockies makes it worth considering for the Denver-to-Chicago leg.