Washington, DC – There are fisticuffs on the White House lawn, soon to be followed by a high-speed race through the National Mall. What is going on in Washington, DC?The United States capital has been transformed in honour of the country’s 250th anniversary.Recommended Stories list of 3 itemslist 1 of 3Trump booed ‘thunderously’ at NBA Finals: What we knowlist 2 of 3US judge refuses to block Trump’s White House UFC fightlist 3 of 3Oval Office octagon: How Trump turned combat sports into a political weaponend of listEvents all around the country are planned to mark two and a half centuries since the signing of the Declaration of Independence on July 4, 1776.The nationwide bash has been dubbed the “semiquincentennial” — meaning half of 500 — and not just because Congress loves long words. The US has a history of throwing itself a party every 50 years.But US President Donald Trump has promised a particularly noteworthy event this year, though the proceedings have been marred by a cavalcade of controversies.Here’s what to know:What is the history of US semicentennial celebrations?The first 50-year anniversary, in 1826, was a considerably more muted affair than the festivities to come.At the time, some of the original signers of the Declaration of Independence were still alive, so the mayor of Washington, DC, invited them to attend the celebration in the capital.Former Presidents John Adams and Thomas Jefferson both demurred, citing their failing health. They died within hours of each other on the day of the semicentennial.Fifty years later, in 1876, the US would mark its 100th anniversary by hosting its first world’s fair, an exhibition featuring displays of art, culture and technology from around the globe.The fair was held in Philadelphia, where the Declaration of Independence was signed, and the original document was put on temporary display in the city.Another world’s fair arrived in Philadelphia for the country’s 150th anniversary in 1926, but it was not nearly as successful. Variety magazine called it “America’s greatest flop”.Meanwhile, the modern template for having a yearlong, cross-country celebration was set on the 200th anniversary in 1976.A train-mounted museum of documents and historical artefacts toured the lower 48 states for 21 months. Volunteers, meanwhile, used covered wagons to travel the width of the country.The celebrations were generally received positively, although the sale of souvenirs — from umbrella hats to mugs — earned it the pejorative “the buy-centennial”.Anthony Geary of Chicago, Illinois, attends the UFC Freedom 250 Fan Fest on June 13 [Matt McClain/Getty Images via AFP]What is happening this year?While the US capital may be the centre of this year’s celebration, there will be a multitude of events across the country. They include: