Manteca’s annual Fourth of July tradition - the 35th annual Three Rivers Powwow - is getting a late start this year.That’s because Independence Day fell midweek.The traditional three-day gathering of Native Americans from all over California and other states is free to the public. Visitors are encouraged to bring their own lawn chairs. More than a dozen vendors will have booths during the powwow selling various Native American arts and crafts as well as food and drinks.