What is the ICAO prefix for United States airports?

What is the ICAO prefix for United States airports?

• A. EG (e.g., EGLL)
• B. EI (e.g., EIW)
• C. K (e.g., KLAX)
• D. C (e.g., CYVR)

Answer: (C)

ICAO airport codes are four-letter identifiers, and the first letter(s) indicate the country or region. For the United States, the usual prefix is K, so most US airports have four-letter codes that start with K followed by the three-letter IATA code. For example, KLAX breaks the pattern as K + LAX, naming Los Angeles. The prefixes shown belong to other countries: EG for the United Kingdom, EI for Ireland, and C for Canada (CYVR). There are exceptions in far Pacific areas, like Alaska and Hawaii, which use PA and PH respectively, but the common rule for the continental United States is the K prefix.