WASHINGTON — Illegal southwest border crossings were down 40 percent last month, according to just released Customs and Border Protection numbers — a sign that President Donald Trump’s hard-line rhetoric and policies on immigration might be having a deterrent effect.

Secretary of Homeland Security John Kelly announced the month-to-month numbers, statistics the CBP usually quietly posts on its website without fanfare.

According to CBP data, the 40 percent drop in illegal southwest border crossings from January to February is far outside normal seasonal trends. Typically, the January to February change is actually an increase of 10 percent to 20 percent.

The drop breaks a nearly 20-year trend, as CBP data going back to 2000 shows an uptick in apprehensions every February.

The number of apprehensions and inadmissible individuals presenting at the border was 18,762 people in February, down from 31,578 in January.

It will still take months to figure out if the decrease in apprehensions is an indication of a lasting Trump effect on immigration patterns. Numbers tend to decrease seasonally in the winter and increase into the spring months.

But the sharp downtick after an uptick at the end of the Obama administration could fit the narrative that it takes tough rhetoric on immigration — backed up by policy — to get word-of-mouth warnings to undocumented immigrants making the harrowing journey to the border.

“Firmness pays,” said Dan Stein, president of the Federation for American Immigration Reform, an advocacy group that supports vastly restricting immigration to the US.

“This is encouraging news,” Kelly said in his statement, citing the increase in apprehensions between October and the end of last year. “However, since President Trump took office on Jan. 20, we have seen a dramatic drop in numbers.”

Kelly noted that fewer apprehensions means fewer people making the dangerous journey north to the border.

DHS has also noticed a corresponding increase in the amount that smugglers, called “coyotes,” are charging to take people to the border — essentially the only way to make it through cartel-controlled smuggling routes.

In some areas, Kelly said, fees have ranged from $3,500 to $8,000.

“We will remain vigilant to respond to any changes in these trends, as numbers of illegal crossings typically increase between March and May,” Kelly said. “However, the early results show that enforcement matters, deterrence matters, and that comprehensive immigration enforcement can make an impact.”

While Stein argues the deterrence only serves to cut down on fraud, however, and legitimate refugees will still make their way to the U.S., opponents of Trump’s policies say his actions mostly harm vulnerable people like women and children that the U.S. system is designed to protect.

“Well, the bullies can gloat and preen that they chased the skinny kids off the block,” said Leon Rodriguez, a former Obama administration director of U.S. Citizenship and Immigration Services. “We need to understand what has occurred here.

“Poor people — in many cases, mothers with children or children alone, fleeing intolerable violence and poverty — have been scared away. Many of those are people with legitimate asylum claims that would ultimately have been granted had they actually reached ports of entry.”