A new research has revealed that more Mexican immigrants are leaving the United States than arriving.

According to the Pew Research Center's recent study of newly available government data from both Mexico and the U.S., the overall flow of Mexican immigrants between the two countries is at its smallest size since the 1990s, generally due to the plummeting number of Mexican immigrants coming to America.

Data from the 2014 Mexican National Survey of Demographic Dynamics (ENADID) indicated that from 2009 to 2014, 1 million Mexicans and their families (including children born in the U.S.) went back to Mexico. In contrast, U.S. census data for the same time period found that around 870,000 Mexicans left their country to head to the U.S., which is a smaller number than the families departing America for Mexico.

Pew's study said that the lessening number of Mexican immigrants to the U.S. is due to several reasons, including the slow recovery of the U.S. economy after the Great Recession that deteriorated the job market. Firmer enforcement of U.S. immigration laws, specifically at the U.S.-Mexican border, may have also driven out the immigrants from America in recent years.

Majority of the Mexicans surveyed by Pew also cited "family reunification" as the primary reason for going back to their country, while 14 percent of migrants said deportation from the U.S. was the explanation behind their return to Mexico.

Mark Hugo Lopez, Pew's director of Hispanic research, said that the era of mass migration from Mexico is "at an end," the report noted. He added, "This is something that we've seen coming. It's been almost 10 years that migration from Mexico has really slowed down."

Mexico is the biggest birth country among the U.S. foreign-born population, with 28 percent of all U.S. immigrants coming from there in 2013, Pew's website wrote. At the same time, Mexico is also deemed as the largest source of unauthorized immigrants in the U.S. Over 16 million Mexican immigrants migrated to America between 1965 and 2015.

Dowell Myers, a public policy professor at the University of Southern California, said that the deficiency of jobs in the U.S. -- not family ties -- is what motivates Mexicans to leave America. SFGate wrote that construction attracts young immigrants the most, but with Mexico's aging population increasing, there's less competition for young people seeking for jobs.

Automakers such as Volkswagen AG, Ford Motor Co., and General Motors Corp. have built plants across central and northern Mexico that provide thousands of jobs and has given rise to auto-parts plants, SFGate added. Construction of highways and rail lines has also gained the attention of more investors.