U.S. President Joe Biden, Vice President Kamala Harris and the nation’s top military officials are due to take part in a wreath-laying ceremony Monday at Arlington National Cemetery as the country observes the annual Memorial Day holiday dedicated to honoring its war dead. Biden, Defense Secretary Lloyd Austin and Joint Chiefs of Staff Chairman Gen. Mark Milley will also speak during a remembrance ceremony at the cemetery located just outside of Washington. “We must remember the price that was paid for our liberties,” Biden said Sunday as he addressed a crowd of veterans and families of fallen service members. “We must remember the debt we owe those who have paid it, and the families left behind. My heart is torn in half by the grief.”   Biden’s remarks came on the sixth anniversary of the death of his son Beau, who served as a major in the Delaware Army National Guard, including a tour of duty with U.S. forces in Iraq before dying of cancer in 2015.President Joe Biden speaks at a Memorial Day event at Veterans Memorial Park at the Delaware Memorial Bridge in New Castle, Del., May 30, 2021.“I know how much the loss hurts,” Biden said. “I know the black hole it leaves in the middle of your chest; it feels like you may get sucked into it and not come out.”    “Folks, you know, despite all the pain, I know the pride you feel in the loved one and— that you lost and those who are still serving — the pride and the bravery in the service to our great American experiment,” he said.  The United States has commemorated Memorial Day to honor its war dead at the end of May since 1868 after the Civil War. The national holiday is now held on the last Monday in May of each year.  To coincide with the holiday, flags are placed by the headstones at Arlington National Cemetery and at many of the other national cemeteries across the country, where many who served in the U.S. military are buried.  The holiday also marks the unofficial start of summer and what traditionally has been a busy travel season in the United States. While travel suffered last year because of coronavirus restrictions, this year Americans are looking to get back to their pre-pandemic routines. More than 1.8 million people went through U.S. airports on Thursday and Friday, according to the Transportation Security Administration.     The U.S. travel group AAA said it expected a 60% jump in travel this Memorial Day from last year, with 37 million Americans planning to travel at least about 80 kilometers (50 miles) from home, mostly by car. The travel boom comes despite higher prices for gasoline.     The price index for typical Memorial Day activities rose this year about 4.3%, faster than the overall consumer price index, according to Reuters. It listed higher prices over pre-pandemic rates for cookout fare such as hamburgers and hotdogs, as well as higher prices for dinner and drinks out, amusement parks, concerts and car rentals. Prices are below pre-pandemic levels for airfare and hotels.  Prices for many goods have been rising because of surging consumer demand as well as supply issues for both materials and labor.