Companies in the United States are growing more cautious about sending their employees on the road, according to a new report from the Global Business Travel Association.

U.S. business travel volume in 2016 is expected to increase just 2.1 percent compared to last year, and spending is expected to grow 1.9 percent.

During the first quarter, the number of business trips originating in the U.S. is estimated to have grown 1.8 percent to 125.8 million, with spending down a hair to $72.7 billion.

The association’s outlook described the trend as “anemic but steady growth.”

“Uncertainty has continued to keep a lid on the growth potential for U.S. business travel,” the report said. “A weak external environment, steep declines in energy prices, lagging earnings growth, and a volatile stock market have all added to corporate jitters.”

The forecast, released Tuesday, was downgraded from expectations in the previous quarter. Last quarter’s outlook was itself downgraded slightly.

In 2015, travelers took an estimated 498.1 million business trips from the United States, an increase of less than a percent compared to the year before. According to the forecast, more than 508 million people in the U.S. are expected to take a business trip this year and spend more than $295 billion.

Jon Gray, vice president of research with Rockport Analytics, which developed insights used in the outlook, said the unknown seems to be weighing on travel plans more than economic realities are.

“It’s hard to say, but most of it is based on just higher levels of uncertainty rather than what’s really going on in the economy,” he said. “It leaves a lot of firms in sort of a wait-and-see mentality, which has sort of led to restrained business travel spending, at least relative to what we saw last quarter.”

Growth is expected to pick back up next year after several current uncertainties are resolved, including the U.S. presidential election and the potential exit of the United Kingdom from the European Union.

“Thankfully, a much brighter 2017 appears on the horizon,” Michael McCormick, GBTA executive director and chief operating officer, said in a statement.

Photo Credit: Travelers at New York-JFK's terminal 4. Skift