In 1991, two men with a love for jazz, Steve Grismore and Mark Ginsberg, shut down a block of Washington Street for a day to allow a few bands to perform in the first year of the Washington Street Jazz Festival.

Now, as it returns for its 22nd season, the Iowa City Jazz Festival, formerly the Washington Street Jazz Festival, is recognized as one of the "Top 10 Festivals in the Nation" by Downbeat magazine.

"It’s great for the whole family," said Grismore, a University of Iowa Jazz Studies lecturer and cofounder of the festival. "It’s just a lot of fun."

The fun begins Friday afternoon with the United Jazz Ensemble kicking things off on the Main Stage and ends on the evening of July 1 with a tribute performance to Paul Motian by Mumbo Jumbo.

During the festival, 24 jazz bands and performers will take one of four stages downtown to showcase their various sounds and talents in the genre.

"I’m always amazed at the quality of performers and the variety of performers that our Music Committee brings in," said Lisa Barnes, the city’s director of Summer of the Arts. "[The members] always brought in these tremendously talented performers."

The Jazz Festival holds such a reputation in the jazz community that "hundreds and hundreds of emails from agents" pour in during the planning with the hope of getting their performers on an Iowa City stage, Barnes said.

Somewhere between 45,000 to 50,000 jazz fans from across the country are expected to fill up downtown this weekend for the festival, which will be located on the Pentacrest, Clinton Street, and Iowa Avenue.

"Not only do we have the Main Stage, but there are three side stages," Grismore said. "One more dedicated to adult local musicians, college-age kids, and more of a youth stage. The youth stage also supports the Senior Center."

Jazz has shifted and expanded since its origin in the early 20th century, and a key element to the style is improvisation.

"Most people consider the beginnings of jazz [to be] around the turn of [the 20th] century," Grismore said. "[It was a] combination of African-American and European-American traditions."

Every decade has brought a new form of jazz. Ragtime, arranged for horn and rhythm sections, dominated the New Orleans jazz scene until after 1910, when it migrated to Chicago and New York City. From there, jazz skyrocketed in new variations in the ’20s and ’30s, playing in speakeasies and by swing bands. The bebop style rolled into the ’40s, followed by cool jazz in the ’50s, the free and fusion jazz of the ’70s, into today’s modern jazz.

"[Jazz today] is an interesting crossover, a blending of different American styles," Grismore said. "World music is also blending with jazz in many ways."

Jazz has become very eclectic, and the Jazz Festival has tried to keep up with it to provide something for everyone to enjoy.

 "I think they try to keep the styles diverse, and there’s a little bit of something for everyone," Grismore said. "Hopefully, what people do when they go is they go with an open mind and actually get turned on to something new."

The Jazz Festival not only hopes to display a wide variety of musicians, the organizers also hope to provide an educational component to the festivities, Barnes said.

This year, jazz musicians will get together at the Mill, 120 E. Burlington St., for Jazz Jam at 10 p.m. all three nights to have a chance to "jam with each other and jam with the community," Barnes said.

On Friday night, Iowa City’s Groove Theory will start things off at the Jazz Jam.

"The nice thing about our group is that everyone is a composer, and they all write, so it allows us to have three to four hours of original material that we get to play," said Cassius Goens, Groove Theory’s drummer and band leader. "With the jam, you know, the really cool thing is we’ll play a couple of our tunes probably, then we open it up for anyone who wants to play some tunes."

It is a great opportunity for local and visiting musicians to play together, he said.

Another educational component of this year’s festival is the inclusion of a new collaboration called Mumbo Jumbo, a tribute to the late jazz drumming legend Motian.

Mumbo Jumbo features Grammy-nominated drummer Matt Wilson, saxophonist Chris Cheek, Grammy-nominated violinist Mat Maneri, guitarist Steve Cárdenas, and bassist Thomas Morgan coming together to play some of Motian’s jazz on the 10-year anniversary of his Iowa City Jazz Festival performance.

"[Motian’s and Bill Evans’ piano trio] really freed up the roles of the musicians," Wilson said. "The bass was more active, and the drums were more active."

Motian performed at the Jazz Festival with his Electric Bebop Band 10 years ago with Cheek and Cárdenas, and the Mumbo Jumbo members look forward to bring back his creative energy and musical freedom, Wilson said.

"He was always sort of reinventing that aspect of it," Wilson said. "That’s why his music was so beautiful."

Before Mumbo Jumbo’s performance, the members will host a panel discussion at noon in the Java House, 211 1/2 E. Washington St., for "people to learn a little more about the jazz world," Barnes said.

"It’s partially to be familiarized," Wilson said. "Once you relate to [the musicians] on a different level rather than just hearing them, you walk away kind of knowing a person, which I think is really great."

Cheek and Cárdenas will be on the panel, and they will speak about Motian as a person and musician and share stories about traveling and playing with him, Wilson said.

Several of the musicians at the festival are playing duets, trios, or quartets together to discover new grooves of jazz through improvisation.

"People are doing this together," Wilson said. "I really think that what’s really intriguing is the aspect of the group effort: working together, offering and receiving sound."