Answer based on context:

Until the mid-20th century most of Yucatán's contact with the outside world was by sea; trade with the US and Cuba, as well as Europe and other Caribbean islands, was more significant than that with the rest of Mexico. In the 1950s Yucatán was linked to the rest of Mexico by railway, followed by highway in the 1960s, ending the region's comparative isolation. Today Yucatán still demonstrates a unique culture from the rest of Mexico, including its own style of food. Commercial jet airplanes began arriving in Mérida in the 1960s, and additional international airports were built first in Cozumel and then in the new planned resort community of Cancún in the 1980s, making tourism a major force in the economy of the Yucatán Peninsula. The first Maya governor of Yucatán, Francisco Luna Kan, was elected in 1976. Today, the Yucatán Peninsula is a major tourism destination, as well as home to one of the largest indigenous populations in Mexico, the Maya people.

Where did commercial jet airplanes arrive later, Mérida or Cancún?
Cancún