Arrests of migrants for illegal southern border crossings have fallen a whopping 75% since May in a sign that President Donald Trump’s hard-line policies are paying off with one of the most dramatic drop-offs in history.

“This is a direct result due to this president’s strategies to address the historic flood of Central Americans, families, illegally crossing the border.”

U.S. Customs and Border Protection said 33,510 people were arrested for border crossing in November, the sixth straight month of decline since May, when 132,000 people — a 13-year high — tried to illegally cross into the U.S. from Mexico, according to a report by The Wall Street Journal.

The majority of migrants detained were families and unaccompanied minors, mostly from Central America and seeking asylum in the U.S. About 9,000 of those arrested in November were families traveling together.

Border crossing arrests typically fall in the winter and pick up in the spring as it gets warmer, but the May-to-November decline this year was still the biggest in “absolute numbers” and second largest of any six-month period ever by percentage in the last century.

From the last few months of the Obama administration into the first few months of the Trump administration, there was a 76% drop, with a smaller peak of 47,211.

“This is a direct result due to this president’s strategies to address the historic flood of Central Americans, families, illegally crossing the border,” CBP Commissioner Mark Morgan said Monday at a press conference. “The network of initiatives have worked and continues to work.”

According to TWSJ, a migrant shelter in Tuscon, Arizona, has seen its arrivals fall from more than 100 a day to less than 40 a day, while a shelter in McAllen, Texas, that opened for migrants, ended up serving other homeless people in the community because it had so much extra space.

“We had a cold front, we had space to allow the homeless to come in and we opened the doors,” Catholic Charities Executive Director and Sister Norma Pimentel told TWSJ.

A shelter in Tijuana, Mexico, also reported its number of migrants housed has dropped from 170 people over the summer to 98 currently, many of which are awaiting their asylum cases to be resolved by the Migrant Protection Protocols (MPP) program, which has sent 54,000 migrants back to Mexico since January.

Immigration experts say the MPP, otherwise known as “Remain in Mexico,” is one of the single biggest factors in the decline in border arrests because those arrested know they’ll have to then remain in Mexico for several months while their cases are decided.

The Trump administration also is looking at ending birthright citizenship.

“I think the big factor has been the Trump administration policies,” Migration Policy Institute Director of Research Randy Capps told TWSJ.