What to know about this weekend's IndyCar race on the National Mall

President Trump speaks as Bud Denker, president of the Penske Corporation, also in a suit and tie, applauds at a Freedom 250 Grand Prix showcase outside the White House in July. Andrew Harnik/Getty Images hide caption

The Freedom 250 Grand Prix is poised to bring dozens of race cars and tens of thousands of spectators to the heart of Washington, D.C.'s National Mall this weekend.

The two-day motorsports event, which culminates in Sunday's marquee 250-mile race, is the first IndyCar race to take place in the nation's capital. And organizers say it might be the last.

"This is a one-time only event, because we're celebrating the country's 250th one time," event chair Bud Denker, president of Penske Corporation, told NPR on Tuesday.

Organizers are promising a patriotic spectacle, with cars zipping through 147 laps of a 1.7-mile route in the shadow of the Capitol building, as well as flyovers and other fanfare. At a preview event in July , President Trump said drivers may reach speeds of 190 miles per hour down Pennsylvania Avenue.

"It wasn't exactly designed for that, but what [Transportation Secretary] Sean Duffy has done with these incredible, brilliant people is really amazing," Trump said.

The unprecedented nature of the event — and the condensed planning timeline — raises many logistical questions. Here's what to know before the green flag kicks things off.

Viewing stands, as seen on the National Mall earlier this week. Andrew Harnik/Getty Images hide caption