The U.S. is paying tribute to those who have died while serving the country

Memorial Day services were held right across the country, as President Biden laid a wreath at The Tomb of the Unknown Soldier.

The sombre day marks the unofficial start to the summer season. But many passengers were left stranded as thousands of flights were cancelled.

The Memorial Day holiday weekend is proving a messy one for many airlines, with carriers canceling thousands of flights worldwide, including hundreds in the U.S. on Monday. 

Thousands of flights were cancelled over the weekend both to and from U.S. cities.

Delta Air Lines was the most impacted with 4 per cent of its operations impacted.

The changes were made due to bad weather and calls from air traffic control.

Delta Airlines assured CBS News that nearly 90 per cent of its customers who were affected on Sunday, had their flight rebooked later in the day.