Mesoamerica is the only place that had true writing prior to 1492. Maya sites in the Yucatan, such as Chichen Itza are actually farther north than Nahua writers in the Triple Alliance or Mixtec writers in Oaxaca.
The writing systems of the Americas were contained within Mesoamerica. The answer to your question, though, depends on what you consider writing. Here's the three possible choices, sorted more less with the farthest "up" Central America first.
Aztecs: The Aztec empire did use a form of writing largely based on illustrative symbols not linked to any language. One could almost think of it as mnemonic aides rather than recording words and sentences.
Assorted Early/Minor Scripts: Many Mesoamerican cultures appear to have had their own writing systems, but very few examples exist for most of them. The Epi-Olmec script is the earliest and appears to contain calendrical information. Schloars have worked out bits of Zapotec writing that seem to indicate personal names and toponyms. Murals at the great central Mexican city of Teotihucan also appear to have glyhpic elements. None of these systems, however, can be said to be readable to any great degree.
Mayan: We know the most about the script used by the Maya. It was a combination of logograms and syllabic signs used on everything from monuments to record historical or mythological events to vessels to describe their contents. The writing is in a dialect of the Cho'lan family, with regionally-varying influences from Yukatek and Cho'rti. We have a large corpus of inscriptions from across the Maya territory and can read a great majority of what they say. So while it is the most southern of these, it is also the most readable and most akin to our own conception of writing by a long shot.
If you're interested in any of these, I'd be happy to recommend further reading or answer questions.
Source: FAMSI
