Nationwide flight disruption stretched into Sunday following cancellations or delays to thousands of flights on Saturday, as the Federal Aviation Administration limited capacity at 40 major U.S. airports amid the longest government shutdown in American history.

As of 5:30 a.m. ET on Sunday, more than 1,100 flights were cancelled across the country according to the FlightAware website, as the FAA grappled with sustained staffing issues in air traffic controller towers and centers.

Saturday saw 1,521 flights canceled nationwide and more than 6,400 flights delayed. 

Saturday’s figures surpassed those from Friday, when 1,024 flights were cancelled. Since Friday, more than 3,700 flights have been cancelled.

Major disruption was expected to continue through Sunday. As of Saturday night, there were over 40 air traffic control staffing triggers at facilities across the country.

The FAA decided not to cut any international flights as it would be a violation of international agreements with the countries, Transportation Secretary Sean Duffy said in an interview on ABC News Live on Friday.

ABC News’ Ahmad Hemingway, Jon Haworth and Nadine El-Bawab contributed to this report.