What is the airport code for Harrisburg, Pennsylvania?

The airport code for Harrisburg, Pennsylvania is MDT, which stands for Harrisburg International Airport. Each airport is assigned a unique three-letter code by the International Air Transport Association (IATA) to identify it easily across various platforms, including airline tickets, baggage tags, and flight information. MDT is specifically designated for Harrisburg International, making it the correct choice for this question.

The other options refer to different airports in other locations. For instance, BDL is the code for Bradley International Airport, serving the Hartford/Springfield area in Connecticut. GSP is the code for Greenville-Spartanburg International Airport in South Carolina, and IAH refers to George Bush Intercontinental Airport, which is in Houston, Texas. Therefore, while these codes are valid, they do not correspond to Harrisburg, distinguishing MDT as the correct answer.