Trump waves green flag kicking off high-speed IndyCar race through Washington

US President Donald Trump was among hundreds of people who gathered to see the IndyCar race through the streets of Washington DC on Sunday, marking the culmination of a series of summer events to celebrate the country's 250th birthday.

The president and First Lady Melania Trump took a ceremonial lap of the 1.7-mile track in his presidential limousine, The Beast.

As they reached the finish line, Trump's new Air Force One completed a flyover above the capital.

The Freedom 250 Grand Prix is the first time professional road racing has been hosted in the capital.

With a maximum speed limit of 55mph (89kmh), Washington DC has the lowest speed limit in the United States.

But on Sunday, some of the world's fastest drivers zoomed past the capital's famous monuments and museums at speeds of up to 190mph (306kmh).

The 25 professional drivers competing in the event face 147 laps featuring seven crucial turns, making a total 250-mile course - a nod to the nation's anniversary.

The drivers sped past the Washington Monument and museums on the National Mall, before passing a finish line with the US Capitol building in frame.

Similar to Formula 1, the IndyCar series is a road race featuring open-wheel, single-seater cars.

But unlike F1, where teams design and build their own cars, the engines in IndyCars come exclusively from Chevrolet or Honda.

Organisers of the Freedom 250 Grand Prix say about 140,000 people are expected to attend, with many given free general admission tickets through a lottery.

However, premium packages sold for $5,000 for a pair of passes.

The event has been a huge logistical and security lift for the city, and has led to widespread road closures, manholes being bolted down, and road resurfacing.

The Ronald Reagan Washington National Airport, which primarily runs domestic flights, has been under a three-hour airspace closure to accommodate the US military flyover.

In other events earlier this summer, Trump hosted an Ultimate Fighting Championship event on the White House lawn, as well as a fireworks show on 4 July.