source: The airport is one of the busiest single runway airports in the country and is a U.S. Customs and Border Protection port of entry.
target: The airport is one of the busiest single runway airports in the country.  It is a U.S. Customs and Border Protection port of entry.
references: The airport is one of the busiest single runway airports in the country.  It is a U.S. Customs and Border Protection port of entry.