A recent report from Airlines for America (A4A), a trade organization for the leading U.S. airlines, predicts that 15.6 million passengers will fly on U.S. airlines over this year’s Labor Day weekend, representing a 4% increase from 2015.

The organization says that it expects 2.3 million air travelers per day from August 31 through Sept. 6, or about 82,000 more travelers per day from the same period last year.

To accommodate the increase, airlines will offer about 2.5 million seats per day, an increase of more than 98,000 from Labor Day weekend last year. Sept. 2 and Sept. 1 are expected to be the busiest days, respectively.

The organization says that airline fares were down about 5% in 2015 and are down 6% so far this year. Cheaper fares make air travel more affordable, resulting in the expected increase for this year’s holiday weekend.

The ten leading U.S. airlines have seen have collectively reported a pre-tax profit of about $12 billion, translating to a profit margin of 15.5%, or 15.5 cents on every dollar of revenue, A4A reports. This is up from last year’s $11.3 billion. The year-over-year improvement is the result of a 1.9% decline in airline operating expenses, as falling fuel prices make up for increased labor, aircraft, and airport costs, the organization reports.

In the first half of 2016, these 10 airlines—Alaska, Allegiant, American, Delta, Hawaiian, JetBlue, Southwest, Spirit, United and Virgin America—have collectively reinvested $9 billion, or $1.5 billion per month, in an attempt to enhance the customer experience. Although this has primarily been through the acquisition of new aircraft, the airlines have also made moves to improve check in areas and gate amenities.

But one area of air travel that has long been in need of improvement is the Transportation Security Administration (TSA).

In May, Peter Neffenger, the head of TSA, said that a shortage of staff combined with a surge in air travel has resulted in chaos for the agency, pushing airport wait times over two hours in places like Chicago. But after the agency was granted approval to put $34 million toward paying extra overtime and hiring 768 new staff by June, TSA reported that long lines at the airport were starting to improve. Adding more lanes and staff during peak periods has been a major facet of the change. Improvements were seen over Memorial Day weekend of this year when TSA reported 93% of people waited less than 15 minutes in regular security lines.