Jazz is sweeping the country this year. For the first time ever, 20 jazz packages, each one different, are appearing in various cities around the United States as part of New York's multifaceted annual summer jazz festival. Some of these have already taken place - not only in New York, but in Washington; San Diego; Philadelphia; Pittsburgh; Atlanta; Hampton, Va.; and Orlando, Fla.
George Wein, who produced the festivals, commented on the Washington concerts:
''We took over all four houses at Kennedy Center. There was such a good reception that they want us to come back next year - we already have the date.''
But the best and most unusual aspect of this event was its flexibility. With one ticket in hand, concertgoers could move around at will from one performance to another in each of the four halls. This is exactly what a festival of this scope needs, and one hopes that the idea can be introduced in New York at Lincoln Center next year.
Although many of the major artists - Ella Fitzgerald, Benny Goodman, Weather Report, etc. - will be repeating performances in the various cities, Mr. Wein is quick to emphasize that the round-the-country festivals ''are not traveling road shows. Each program is a different package, designed uniquely for its respective city.''
How could he be sure of the reception these jazz festivals would receive in the cities?
''We chose major cities for the most part. And I wanted to bring established names to the new cities to show the quality of what we had in mind. We opened in Pittsburgh with a free concert with Ella, for example.''
So far the reception seems to have been warm, and Mr. Wein looks forward to another year of festivals around the country.
''We'll probably do the same cities next year. It takes a little time to build up to get success across the board. So it's a little spotty the first time around, but if we stay in those cities, hang in there with them. . . .
''How can you call this work? This is fun. I enjoy it!''
At the New York edition of the festival, audiences had several choices every evening: from an avant-garde afternoon at Avery Fisher Hall to what has now become a favorite event - an evening of big-band music for listening and dancing at Roseland Ballroom, this year with the Count Basie and Sy Oliver orchestras.
The ''World Saxophone Quartet Meets the Four Brothers'' concert was a study in contrasts. The first half featured the ''World'' group - four saxophonists (Hamiet Bluiett, Julius Hemphill, Oliver Lake, and David Murray) who have earned considerable acclaim over the past few years in a series of provocative and innovative compositions that displayed both harmonic and rhythmic skill.
The four men employed various reed instruments - bass and contrabass clarinets and flutes, as well as most of the saxophones - to produce a variety of colors in their music. Unfortunately, the solos, for the most part, were not of the same high caliber as the writing.
The ''Four Brothers'' - the name for the original Woody Herman saxophone section, and the name of the famous jazz tune by Jimmy Giuffre - had Giuffre on tenor sax, joined by three of the original ''Four Brothers'': Al Cohn, Zoot Sims , and Stan Getz.
What could have been a wonderful reunion turned out to be rather drab, perhaps because Zoot Sims wasn't quite up to snuff, Giuffre just isn't a great soloist, and the rhythm section sounded out of sync half the time (Monitor problems, perhaps)? In fact, sound problems marred several of the concerts. The piano, for instance, was miked appropriately low in some of the vocal concerts but wasn't turned up when the pianists had a solo spot.
But the one concert that stands out - it is difficult to find enough adulatory words to describe it without getting downright excessive - was the Mabel Mercer, Eileen Farrell collaboration, ''Listen to the Words.'' Most of the praise must go to Mabel Mercer, who, in her 82nd year, is capable of holding an audience absolutely spellbound with her singing/talking renditions of the great American popular songs.
It's hard to say where the songs merge into poetry and vice versa, but it really doesn't matter. Mercer does it all with such grace, such comprehension of the meaning of both lyric and music, that there isn't a musician around, vocalist or instrumentalist, who couldn't benefit from spending just one afternoon with Mabel Mercer. Although Miss Farrell lacks that special magic, she proved a personable enough other half for this ''sister act,'' as she called it.
Coming up: Cincinnati, today through July 17; Minneapolis-St. Paul, today through 18; Seattle, July 30-Aug. 6; Milwaukee, Aug. 11-15; Newport, R.I., Aug. 21-22; Chicago, Aug. 30-Sept. 5; Detroit, Sept. 1-6; Houston, Sept. 16-19; New Orleans, Sept. 17-19; Dallas-Ft. Worth, Sept. 23-26; Los Angeles, Nov. 6-10; San Francisco, Nov. 6-12.