Which airport code corresponds to Washington, D.C., specifically Dulles?

The airport code for Washington, D.C.'s Dulles International Airport is IAD. This code is significant because it directly relates to the airport's official designation, which helps in identifying it within the global airport system.

Dulles International Airport, opened in 1962, serves as a major hub for international flights and is located in Virginia, not far from Washington, D.C. The IAD code is derived from the name of the airport, specifically from "Dulles," which facilitates passenger and airline communication, booking, and logistics.

Other choices, such as IAH, GSP, and ILM, do not relate to Dulles International; instead, they correspond to other airports in different locations. For example, IAH is the airport code for George Bush Intercontinental Airport in Houston, Texas, while GSP stands for Greenville-Spartanburg International Airport in South Carolina and ILM designates Wilmington International Airport in North Carolina. Understanding these airport codes is crucial for travel planning and navigation in aviation.