For Denver International Airport (DEN/DIA), you do not strictly need a reservation to park in the primary airport-owned lots (Garage, Economy, or Shuttle lots), but in 2026, it is highly recommended due to record-high passenger volumes. The airport offers a "Reserved Parking" program for the East and West Garages, which guarantees you a space even when the lots appear "Full" on the highway signs. If you do not have a reservation, you must rely on real-time availability, which can be checked on the flydenver.com website. During peak travel periods like Spring Break or the holidays, the Economy and Pikes Peak shuttle lots frequently reach capacity by Tuesday or Wednesday. If you choose an off-site private parking company (like The Parking Spot or WallyPark), a reservation is almost always required to secure the best rates and ensure a spot is held for your vehicle before you arrive at the facility.