MODESTO — More than 20,000 people expected to line the streets of downtown Modesto for the Valley town’s 139th Annual Fourth of July Parade.“The longest running Fourth of July Celebration in California is coming back to Modesto,” said parade chairman Jeremiah Williams. “We have about 120 floats, walking entries and semi trucks that are about 84 feet long. Another nice feature we have going on is an 80-foot balloon arc that the entries will go through during the parade.”The “Proud to be an American” parade will begin at 9:30 a.m. Thursday along 10th and F streets and it will wind through downtown Modesto ending on I and 17th streets.“Also coming back this year will be the Modesto’s Farmers Market,” said Williams.