The find is now the largest of its kind, reports the news agency AP. The archaeologists who work at the site believe they will find many more.
The site where the new Santa Lucia airport is to be built was at one time close to a lake, where the mammoths were probably stuck in the mud.
According to archaeologist Rubén Manzanilla López, several traces of human activity have been found, including tools made of mammoth bones.
They have also found several pits that probably served as traps, and signs that the mammoths were cut up by humans after dying in the mud.
Similar traces have also been found elsewhere in Mexico.
The archaeologists who work at the site hope the findings can shed light on the reason why the mammoth died out between 10,000 and 20,000 years ago.
– There is an eternal discussion about what caused the extinction of these animals, whether it was climate change or humans. I think the conclusion in the end will be that it was a combination of climate change and human presence, says paleontologist Joaquin Arroyo Cabrales.
Finds of large groups of dead mammoths are rare. Similar finds have been made in Siberia and outside Los Angeles, but this is far greater.
According to Captain Jesus Cantoral of the Mexican Army, who is leading the construction of the airport, more and more skeletons are being found.
Each time an area is to be excavated, it must be examined. However, the construction site is so large that the work can continue elsewhere while archaeologists take over any finds.
The airport is scheduled to be completed in 2022.