Alternative band Wilco has extended its summer tour plans yet again. A week after announcing a month-long round of concerts in June, frontman Jeff Tweedy and his acclaimed group have added a new block of shows for July and tacked on a few new gigs to the previously announced dates.

The 20-date summer tour is now set to open June 12 at Aronoff Center for the Arts in Cincinnati, OH, and run through the group’s July 23 appearance at the four-day 10,000 Lakes Festival in Detroit Lakes, MI. The new July portion of the trek picks up July 3 at Red Rocks Amphitheatre in Morrison, CO.

Conor Oberst and the Mystic Valley Band will provide tour support, beginning July 8 at the Wolftrap in Vienna, VA, and continuing through July 19 at Art Park in Lewiston, NY. However, Oberst and his backing musicians are not on the bill for Wilco’s July 13 performance at Keyspan Park in Brooklyn, NY.

Pre-sales are currently open for most dates on the July leg of the tour. Tickets for Wilco’s previously announced two-night stand at The Wiltern in Los Angeles on June 22-23 are available to the public starting today, April 24.

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Wilco recently completed mastering its next studio album, which is currently scheduled for a June release on Nonesuch Records. Though the project is still untitled, according to the band’s official Web site, a complete track list has been confirmed.

Wilco opened its 2009 touring season on April 14-15 at Pabst Theater in Milwaukee, WI, the first stop on a brief nine-city run. The tour leg ends with an April 25 performance at the New Orleans Jazz & Heritage Festival in New Orleans, LA, after which the band will perform a few late May gigs in Spain and Portugal. After their late July festival gig, the band members will head back overseas for a month-long tour of Europe in August.

Wilco updated itinerary:
(Dates are subject to change.)

June 12 Cincinnati, OH Aronoff Center for the Arts
June 13 Manchester, TN Bonnaroo Music Festival
June 15 Oklahoma City, OK Coca Cola Bricktown Events Center
June 17 El Paso, TX Abraham Chavez Theatre
June 18 Tucson, AZ Centennial Hall
June 19 Las Vegas, NV The Joint
June 20 Pomona, CA Fox Theater
June 22 – 23 Los Angeles, CA The Wiltern
June 27 Berkeley, CA Greek Theatre
June 28 Stateline, NV Harveys Lake Tahoe Outdoor Arena
June 30 Jacksonville, OR Britt Festival
July 3 Morrison, CO Red Rocks Amphitheatre
July 8 Vienna, VA Filene Center At Wolf Trap
July 10 Wilmington, DE Frawley Stadium
July 11 Lowell, MA LeLacheur Park
July 13 Brooklyn, NY KeySpan Park
July 17 Portland, ME Maine State Pier
July 18 Fishkill, NY Dutchess Stadium
July 19 Lewiston, NY Earl W. Brydges Artpark
July 23 Detroit Lakes, MN 10,000 Lakes Festival