When most Americans head off to work, they jangle their car keys. Joseph Kopser fires up his cellphone. The CEO and founder of RideScout, an app that aggregates transportation options, might decide to board the bus. Or he could catch a cab. Or he could swing by the nearest Capital Bikeshare station.

There are so many alternatives that let you ditch your wheels in D.C. that it’s overwhelming just to keep track of them all.

“I thought, ‘Surely, with technology, someone has put this all together,’ ” says Kopser, who realized two years ago that that someone was going to have to be him. The free app is still a work in progress — he’s asking folks in D.C. to download it now and offer feedback before its official launch here in November.

This weekend, there’s an especially good reason to try it out: Our annual Car-Free Day celebration has expanded to 72 hours (it’s Friday through Sunday). That leaves triple the time to travel by bus, train, bike or carpool.

The benefits of participating are huge. And I’m not just talking about saving money and saving the planet. Everyone who pledges to take part through carfreemetrodc.com is eligible for prizes, including an iPad, a Bikeshare membership, a restaurant gift certificate and more.

Not sure where to go without your car? I’d suggest a parking space. Friday is also PARK(ing) Day, a global movement that promotes reimagining those rectangular pieces of asphalt as places to hang out. It’s amazing what a single space can become — if only for a few hours.

The District has had a handful of groups organize these parklets over the past several years, but for the first time, the District Department of Transportation decided to get involved and encourage participation.

“We had talked about it before and finally got it together this year,” says Sam Zimbabwe, associate director for planning, policy and sustainability, who boasts that D.C. will have 17 of the parklets this year. That’s a tiny fraction of the city’s 18,000 metered spaces, but it’s enough to capture people’s attention and get them thinking creatively about how city streets can be used.

Several parklets are being organized by D.C. agencies. DDOT, for instance, is using its space (700 F St. NW) to throw a third birthday party for Capital Bikeshare. A whole bunch will be in Georgetown, including at least two with a cafe theme. Malmaison (3401 K St. NW) will host a pop-up library with complementary samples of juice, coffee and pastries, while CycleLife USA (3255 K St. NW) will offer bike parking and more free coffee.

And a few others will be situated downtown but designed to make visitors feel far removed from the city. The Landscape Architecture Foundation (1900 M St. NW) plans to drag in hay bales, dogwood trees and grass into its parking space — and promises to reward anyone stopping by with a “recreational element.” Fittingly, the National Wildlife Federation (901 E St. NW) is transforming its space into a “certified wildlife habitat,” hosted by mascot Ranger Rick.

It’s a lot to see in one day. Good thing you won’t need to worry about your car.

Check out a map of the area’s PARK(ing) Day spaces at caseytrees.org.