From a command center in Mexico's capital, student activists tracked election irregularities reported in local media, and encouraged others to document activities at their neighborhood polling stations.
The monitoring effort was spearheaded by youth who have led a series of social media campaigns and street protests leading up to Sunday's vote.
At the Revolution elementary school near the heart of Mexico City, Martha Rojas Ramos was near the front of the line, waiting for the polls to open Sunday morning.
The 58-year-old flea market merchant, who carried bags of merchandise in her arms as she waited in line to vote before heading to work Sunday morning, said money was tight, and the economy was a key issue for her in this year's election. Peña Nieto, she said, is the right person to solve Mexico's economic problems.
"He is obviously prepared. There was obviously a dirty war against him," said Martha Rojas Ramos, 58.
Critics lamenting the possible return of the PRI to power aren't thinking straight, she said.
"That's all in the past. What's important is that he is young and has all the ability to represent us," she said.
Alejandro Garcia, a 33-year-old accountant, said he supported Peña Nieto's security strategy, which aims to decrease violence in Mexico.
Calderon, Mexico's current president, made combating cartels a top priority when he took office in December 2006. Since then, more than 47,500 people have died in drug-related violence nationwide, according to government statistics.
Garcia said the surge in violence has negatively impacted daily life throughout the country.