Seoul to Denver (ICN–DEN) — Airlines, Schedules & Connections

South Korean passport holders enter the United States under the Visa Waiver Program (VWP) for up to 90 days for tourism or business. You must obtain an approved ESTA (Electronic System for Travel Authorization) at esta.cbp.dhs.gov before travel. The ESTA costs $21, is processed within 72 hours (often minutes), and is valid for 2 years or until your passport expires, whichever comes first. Passport must be a biometric e-passport.

At US immigration, you clear CBP (Customs and Border Protection) where an officer reviews your ESTA, asks about your trip purpose, takes fingerprints and a photo, and determines your allowed stay (up to 90 days). Have your return ticket, hotel booking, and a general idea of your itinerary ready to answer questions. The 90-day VWP stay cannot be extended, and overstaying voids your ESTA and future VWP eligibility. For stays beyond 90 days or work purposes, apply for a visa at the US Embassy in Seoul.

Direct flights from Seoul Incheon to multiple US cities run 10 to 14 hours: Los Angeles (LAX) 11 hours, San Francisco (SFO) 11 hours 30 minutes, New York JFK 14 hours, Seattle (SEA) 10 hours, Dallas (DFW) 13 hours, and Atlanta (ATL) 14 hours. Korean Air, Asiana, Delta, United, and American all operate transpacific routes. The US uses the US dollar. No mandatory vaccinations. Global Entry ($100, valid 5 years) includes ESTA and provides expedited entry through automated kiosks at major US airports, a strong investment for frequent visitors.

AREX (Airport Railroad Express) runs two services from Seoul Station: the Direct Train (43 min, ₩11,000, reserved seats) and the All-Stop train (66 min, ₩4,550, unreserved). Both trains serve T1 first, then T2; confirm which terminal your airline uses before boarding.Limousine buses depart from major Seoul neighborhoods and hotels (₩16,000–18,000, 60–90 min depending on traffic). KAL and LIMOUSINE services are reliable. Taxis from central Seoul cost ₩65,000–80,000 and take 60–90 minutes. Deluxe (black) taxis are pricier but English-speaking drivers are more common.

RTD A Line runs to Denver Union Station (37 min, $10.50) with connections to light rail and bus routes. Taxis have meters; expect $55–65 to downtown.DEN's tent-roof Jeppesen Terminal is a single building; all three concourses connect via the underground automated train. Rental cars are on level 5. For ski resorts, shuttle services depart from Ground Transportation.

Semi-arid with 300+ days of sunshine. Summers are dry and warm (27–34°C) with afternoon thunderstorms that produce dramatic but brief delays. Winters bring cold temperatures (−8 to 5°C) and heavy blizzards that can shut down ground operations.

Spring snowstorms can be heavier than midwinter ones. Altitude (5,430 ft) means low humidity year-round; stay hydrated.