To enter a United Club lounge based on frequent flyer status, you typically need United Premier Gold, Platinum, or 1K status (which corresponds to Star Alliance Gold). However, a key caveat is that United elites can generally only access domestic United Clubs when they are traveling on an international itinerary operated by a Star Alliance carrier. If you are flying strictly within the U.S., even 1K members do not get "automatic" lounge access unless they have a separate United Club membership or a high-end credit card like the United Club Infinite. For the more exclusive United Polaris Lounges, status does not matter; you must be flying in a long-haul international Polaris business class seat to gain entry. Other ways to get in include having a one-time pass (often provided by the United Explorer card) or being a Star Alliance Gold member from a different airline's program (like Lufthansa or Air Canada), which allows for access even on domestic U.S. flights.