WASHINGTON >> Customs officers stationed at the U.S. border and at airports searched an estimated 30,200 cellphones, computers and other electronic devices of people entering and leaving the United States last year — an almost 60 percent increase from 2016, according to Homeland Security Department data released today.

Despite the surge, Customs and Border Protection officials said the searches affected fewer than 1 percent of the more than 300 million travelers who arrived in the United States last year.

Homeland Security officials say border searches are an important investigative tool and are used sparingly by its agents.

“In this digital age, border searches of electronic devices are essential to enforcing the law at the U.S. border and to protecting the American people,” said John Wagner, deputy executive assistant commissioner at Customs and Border Protection.

Wagner said the agency was committed to preserving the rights and civil liberties of travelers whose devices are searched.

Searching people and packages at the border is a long-standing practice, dating to the founding of the United States. But they have taken an added significance in President Donald Trump’s administration, which has promised to limit both illegal and legal immigration to the United States.

Privacy and immigration advocates see the increase in searches as part of the administration’s overall immigration agenda, which includes a travel ban against several Muslim-majority countries and rescinding an Obama-era program that allowed unauthorized immigrants who were brought to the United States as children to live and work in the country without fear of being deported.

The Trump administration also has proposed a 1,000-mile border wall — along nearly half the Southwest border — that Homeland Security officials estimate would cost about $18 billion, according to a congressional aide who spoke Friday on the condition of anonymity. The new wall tally and length of the border wall was first reported by The Wall Street Journal.

Privacy activists and those who have been detained at the border say the examination of their phones, computers and hard drives are invasive and violate Fourth Amendment protections against unreasonable searches.

But courts have long held that those protections do not apply at the border or airports because of the government’s compelling interest in combating crime and terrorism.

A 2014 Supreme Court ruling did say, however, that law enforcement needed to have a warrant to search electronic devices when a person was being arrested.

But since that case did not involve a search at the border, Homeland Security officials said the ruling did not apply to Customs officers, who argue that the examination of electronic devices is akin to searching the luggage of travelers entering or exiting the United States. Customs officials also say the search of electronic devices has led to the arrests of individuals caught with illegal material, such as child pornography.

But privacy advocates say smartphones and other personal electronics contain far more sensitive personal information, such as banking and medical records, than suitcases.

The American Civil Liberties Union and the Electronic Frontier Foundation have filed a lawsuit in Boston arguing that a warrant should be required to search such devices at the border. Ten U.S. citizens and one immigrant — including several Muslims and other minorities — are named in the lawsuit.

The Trump administration has asked a judge to dismiss the case.