This Festival has been going on for decades, with a 3 year interval recently whlie the park was refurbished. Glen Echo used to be an amusement park and was purchased by the Park Service after it closed. The stages are still called "Crystal Pool," "Bumper Car Pavilion," etc.   
(As a kid I went on those rides....)

There are a number of artists in residence and classes in the arts take place all year round as well as puppet shows, dances and other events.

The Washington Folk Festival not only gets a huge audience, including literally thousands of people who normally don't go to many ethnic and folk activities, but it also can draw from a huge selection of talents. We have a wide variety of ethnic populations who still maintain their traditions of music, dance and storytelling. Plus of course the Folklore Society of Greater Washington and related performers.

And you can ride the carousel.