A ground delay is impacting O'Hare International Airport on Saturday morning as union members of the Federal Aviation Administration (FAA) picketed outside.

Follow live updates as flight reductions begin today at 40 high-traffic airports in what officials have described as a "proactive" effort to alleviate pressure points.

Travelers with upcoming travel plans can expect to see fewer flights to many major U.S. cities. The Federal Aviation Administration reduced traffic across 40 airports starting Friday to ease the load on the nation’s air traffic controllers.

San Francisco International Airport was among the major U.S. air-travel hubs to face cancellations as the federal government places limits on air travel.

"This is about where’s the pressure and how do we alleviate the pressure," Transportation Secretary Sean Duffy said.

At International Airport, things were still running smoothly on the first day of reductions. However, while isn't among the 40 airports directly affected, flights departing from here are heading to destinations that are.

HOUSTON — The Federal Aviation Administration is warning of a ground delay at George Bush Intercontinental Airport (IAH) from 4 p.m. to 8:59 p.m. Saturday as the government shutdown drags on. The FAA said flights departing from Bush Airport are delayed on average by 42 minutes due to staffing issues.

Orlando International Airport is one of 40 airports having to reduce flights by ten percent because of the government shutdown.