In his proposed budget, which was released last week, President Trump included a 13 percent cut ($2.4 billion) to the national Department of Transportation (DOT) budget.

“The Budget reduces or eliminates programs that are either inefficient, duplicative of other Federal efforts, or that involve activities that are better delivered by States, localities, or the private sector,” it says in the document.

Although, according to Secretary of Transportation Elaine Chao, it is still too early to tell how the proposed budget will affect DOT operations (the Office of Management and Budget will not release the final budget for 2018 until May), the budget will undoubtedly affect the way many Americans and foreign visitors travel across the country.

Airports

Earlier this month, the Trump administration proposed cuts to the TSA and Coast Guard budgets to pay for a wall on the border between the U.S. and Mexico. The budget slash would eliminate several key counter-terrorism initiatives, including pilot training in event of an armed takeover, a grant program for law enforcement officials at airports and a program to send agents on airport sweeps.

At the time, Ozzie Nelson, national security expert for think tank the Center for Strategic and International Studies (CSIS) and former counter-terrorism official, told Travel + Leisure that “diverting resources away from the industry that is probably arguably most targeted by terrorists groups just doesn’t make a lot of sense.”

The budget would also cut funding to the Essential Air Services, a program which provides grants to smaller, rural airports around the country that are not able to financially sustain themselves on their own.

Amtrak

The budget proposes cutting “Federal subsidies to Amtrak to focus resources on the parts of the passenger rail system that provide meaningful transportation options within regions.” This would mean that smaller, regional lines would be forgotten in favor of improving Amtrak’s Northeast Corridor (the route that runs through Boston, New York City, Philadelphia and Washington, D.C.) — which is the railway’s most profitable and most-ridden line.

The plan “terminates Federal support for Amtrak’s long distance train services, which have long been inefficient and incur the vast majority of Amtrak’s operating losses.” For passengers on the ground, that means that Amtrak would only operate in 23 states and would eliminate the famous California Zephyr route, which connects Chicago to San Francisco.

In a statement, Amtrak CEO and President Wick Moorman said that the budget cut would affect 500 communities around the country. It could also affect the profitability of the Northeast Corridor by eliminating many of the smaller routes which feed into it.

Roads

Trump’s budget would cut funding to the Transportation Investment Generating Economic Recovery (TIGER) grant program, put in place by the Obama administration in 2009. In the eight years that the program has existed, it has distributed over $5.1 billion to cities and states to build “everything from ports to rails to transit to highways,” Beth Osborne, senior policy adviser for Transportation for America, said at a Senate hearing last week.

Supersonic Flight

In an unexpected twist, the Trump budget calls for a $624 million investment in aeronautics research and development for “eventual over-land commercial supersonic flights and safer, more efficient air travel.”

The last supersonic commercial flight to travel over American land was the Concorde in 2003. Service was stopped due to a combination of low passenger numbers, economic inefficiency, and the disruptive noise pollution the aircraft left in its wake.

This article originally appeared on TravelandLeisure.com