Trump complains about a "massive inflow" of immigrants to the U.S. The numbers suggest otherwise.

President Donald Trump has spent three days warning about the "big caravans" of immigrants who want to enter the United States, demanding that Mexico and Congress stop the "large flows of people" to the southern border.

“Congress must immediately pass Border Legislation, use Nuclear Option if necessary, to stop the massive inflow of Drugs and People,” Trump tweeted. “Our country is being stolen!”

But Trump is missing key information. The inflow of immigrants across the border with Mexico is not massive. In fact, it has declined steadily and is at its lowest since 1975, according to official data.

Since 2000, which was the year that saw the largest number of detentions on the border in the past 40 years, arrests have decreased 80%.

Last year border agents detained 303,916 people. In 2000 that number was 1,643,679.

Despite the data, Trump continues to warn the country of "large flows of people" entering the southern border "to take advantage of DACA." That is despite the fact that the government no longer even accepts new applicants to the DACA program, which benefits undocumented immigrants who entered the country as children over 10 years ago.

During the month of February, arrests of undocumented persons on the southern border increased 2.4%.

But that phenomenon is not an aberration. The Office of U.S. Customs and Border Protection (CBP), which is regularly congratulated by the president, explains that the slight increase in February is normal at this time of year.

"This is typical of migration patterns in the month of February," explains CBP.

Fewer Mexicans, more Central Americans

To a large extent, the reduction of migratory flows to the U.S. is explained by the smaller number of Mexicans now crossing the border.

In 2000, authorities detained 1.6 million Mexicans on the southern border. Last year that figure was 130,454 people, according to CBP data.

This coincides with figures from Mexico’s National Institute of Statistics and Geography (INEGI). Between 2008 and 2015, 43.5% fewer Mexicans left their country—from 64.1 to 36.2 per 10,000 inhabitants.

However, migrants from other countries–mainly El Salvador, Guatemala and Honduras–to the United States increased more than 500%.

2017 was the third year on record with more non-Mexican than Mexican immigrants arrested on the southern border: about 175,000.

In recent days, Trump has attacked Mexico for not stopping Central American migrants from passing through its borders on the way to the United States.

Trump tweeted about the group of more than 1,000 migrants - mostly Central Americans - who left Tapachula, Chiapas, about a week ago on their way to the U.S. border, referring to them as “caravans.”

“Mexico is doing very little, if not NOTHING, at stopping people from flowing into Mexico through their Southern Border, and then into the U.S. They laugh at our dumb immigration laws,” Trump wrote on Twitter.