Correction: An earlier version of this story incorrectly said passenger traffic at Nashville International Airport was up 1.3 percent in 2016. It was up 11 percent. This version has been corrected.

Security checkpoints at BWI Airport, which saw a record number of passengers last year. (Astrid Riecken/For The Washington Post)

More than 70 million passengers flew through the Washington region’s three airports in 2016 — a sign that airport leaders’ aggressive efforts to court new airlines, offer amenities and upgrade shopping and dining options are paying off, officials said.

Last year, both Baltimore-Washington International Marshall and Reagan National airports set records for the number of passengers who passed through their gates. Even Dulles International Airport, which has struggled to attract travelers in recent years, posted a small but significant gain, fueled largely by international travelers.

This was the sixth straight year of record-breaking growth for National and the second consecutive year that BWI has set a record for passenger travel.

In all, 25.1 million passengers flew through BWI in 2016, making it the region’s busiest airport. More than 23.6 million passengers traveled through National. Roughly 21.8 million flew through Dulles.

The airports’ gains come at a time when the number of people traveling by commercial air is at an all-time high. In March, the Bureau of Transportation Statistics reported that 929 million passengers flew in 2016, an increase of 3.5 percent over 2015, the previous record year.

“Our airports have done fairly well,” said Kevin Burke, president of the Airports Council International-North America, a trade group that represents airport owners and operators. “People have more cash. They’re spending money, and they’re traveling more.”

Indeed, across the country, airports of all sizes reported a boon in passenger traffic.

Officials at San Francisco International said that 53.1 million people flew through the airport in 2016, its sixth straight year of gains. Omaha’s Eppley Airfield had about 4.3 million passengers in 2016, up from 4.2 million the previous year. Even Nashville International reported growth with 13 million passengers in 2016 — up 11 percent from the previous year.

Industry experts say the gains are fueled in part by a strong economy and low fuel prices. The Washington region has fared better than many because of its ties to the federal government.

“People don’t fly until they feel comfortable about spending their money,” said Ricky Smith, chief executive officer of BWI. He said the strength of the region’s economy, coupled with BWI’s ability to attract low-cost carriers, have helped fuel BWI’s growth.

BWI also has benefited because it serves as a hub for Southwest Airlines, which is the dominant player at the airport. Roughly 70 percent of the flights at BWI are on Southwest. According to Transportation Department figures, in 2016 the airline carried more total system passengers than any other U.S. carrier, surpassing the previous leader, American Airlines. Southwest also chose BWI as one of its gateway airports when it launched international service in 2014.

The airport also has been able to attract low-cost carriers including WOW air, which launched service to Reykjavik, Iceland, in 2015 and expanded its offerings in 2016. Last December, Norwegian, another low-cost carrier, began offering service between BWI and two Caribbean islands — Martinique and Guadeloupe.

At a time when infrastructure is making headlines, the airport also recently launched a $60 million expansion of its international terminal, which is expected to be completed next year.

Margaret McKeough, chief operating officer at the Metropolitan Washington Airports Authority, which manages National and Dulles, said other trends have helped boost traffic. Some airlines have replaced smaller commuter aircraft with larger planes. In the past, airlines that would have made service adjustments twice a year are now making them quarterly in response to traveler demand, McKeough said.

McKeough said officials are predicting growth for the two airports this year, as well.

“Growth is definitely on the horizon,” she said.

Officials have launched a $1 billion building program at National that includes construction of a new concourse for short-hop flights, as well as an expanded security screening area and new parking garages.

Even so, much of their attention has been focused on improving the fortunes at Dulles, once the region’s dominant airport. Passenger traffic at the airport peaked at 27 million in 2005. In 2015, its passenger counts were surpassed by its smaller sister airport, National. Dulles now serves roughly 22 million passengers a year.

Virginia Gov. Terry McAuliffe (D) is among those who have made Dulles a special focus. He championed legislation that will invest $50 million in the airport over the next two years. The money will be used in part to lower the costs for airlines operating out of Dulles in hopes of making it more competitive with other airports. McAuliffe also was part of a delegation that made the successful pitch to Air India, which is expected to launch new nonstop service to New Delhi this summer.

Even with robust passenger counts, airport officials are well aware that the strength of the region’s economy could be tested in coming years with the Trump administration’s focus on reducing the federal workforce and slashing the budget of nondefense-related agencies. Another concern is whether Trump’s proposed budget cuts will impact the Transportation Security Administration, which is responsible for domestic passenger screening.

Burke, the trade group president, recalled the long lines that greeted passengers last year in airports across the country. TSA, he said, still remains “woefully under budget.”

But it is hard to know what the impact will be until more details are available, Burke said.

Airport officials also say it is too early to predict whether the ban on electronic devices on direct flights on eight non-U.S. airlines from eight Muslim-majority countries will have an impact on their operations. In part, it will depend on whether passengers opt to fly with other carriers.

The question is particularly significant for Dulles, where international flights have been one of the few bright spots. Six of the nine airlines covered by the ban offer direct service to Dulles from countries subject to the electronics ban, which went into effect late last month.

Also still unknown: the fate of President Trump’s ban on travelers from certain Muslim-majority countries. A federal court judge in Hawaii last week extended a temporary hold on the measure that would suspend new visas for travelers from six countries: Iran, Somalia, Sudan, Libya, Yemen and Syria.

Officials with the Global Business Travel Association fear that if the ban is put into place, it could prompt companies to curtail employee travel.

Nevertheless, airport officials remain optimistic.

“I don’t know when our 19-month streak will come to an end,” BWI’s Smith said. “But our challenge is to manage our growth and make sure our facilities are capable of handing passengers. We are an easy-come easy-go airport — that is one of our attractions.”