Why is Mexico City in central Mexico?

It is a city in central Mexico (19° 25' 57.85'' N, 99° 07' 59.71'' W) with an elevation of 2,240 meters above sea level (about 7,349 feet) and some 380 Kilometers (236 miles) to the closest beach (Tecolutla, on the Gulf of Mexico).

Before 1325 AD, the Aztec or Mexica people were a nomadic tribe that wandered throughout the land, looking for a place to settle and build their capital. Their state religion awaited the fulfillment of an ancient prophecy: the wandering tribes would find the destined site for a great city whose location would be signaled by an eagle eating a snake while perched atop a cactus. The Aztecs saw this vision on what was then a small swampy island in the middle of lake Texcoco, after which they founded their capital Tenochtitlan (today known as Mexico City), on March 13, 1325.

The prophesy and subsequent vision is now immortalized in Mexico's coat of arms and on the Mexican flag.