Presidential travel is always an expensive proposition, requiring elaborate security measures, including a sizable Secret Service detail. With a jet-setting first family such as the Trumps, the costs quickly balloon.

It’s not only that millions are drained from the public coffers each time President Trump takes a golf break at one of his resorts — which he does with marked frequency. When his adult children head out on holiday or to promote the family business, taxpayers must subsidize their adventures as well.

The exact amounts are hard to come by, but what is known is jaw-dropping. In a one-month period in early 2017, the president spent $13.6 million on just four trips to his Mar-a-Lago property in South Florida, according to estimates by the Government Accountability Office. That’s an average of $3.4 million per trip — at minimum. The actual price tag is most likely higher, the agency noted in a report released last February, but greater accounting precision was impossible because the White House refused multiple requests for information. Compounding the challenge, the Secret Service tends to be lax in fulfilling its reporting requirements.

As president, Mr. Trump has visited his properties outside the Washington region more than 50 times, according to The Washington Post. His sons Eric and Donald Jr. have taken business trips to far-flung locales including Dubai, Ireland and India. A single visit in 2017 by Eric Trump to a Trump property under construction in Uruguay cost taxpayers nearly $100,000 just in hotel bills for Secret Service agents and embassy staff members.