The first-time candidate collected 48.5 percent of the vote to win the election by about 1,500 votes.
Republican attorney general candidate Mike Gibbons conceded the Missouri attorney general race to Democrat Chris Koster.
Missourians passed all the intiatives and constitutional amendments on the ballot. They included an English-only amendment to the state Constitution, expanded options for stormwater bonds, established a home-care attendant council and increased required renewable energy sources for publicly owned utilities to 15 percent.
After an election that garnered one of the highest turnouts in Columbia's history, at watch parties scattered around the city, residents of Columbia welcomed the new President-elect Barack Obama with excitement and cheers.
City voters approved a measure to issue $38.9 million in bonds to finance future renovations and additions to the city's water system over the next six years.
As members of the NAACP gathered around the big-screen television at Second Baptist Church to hear President-elect Barack Obama give his acceptance speech, the pride in their eyes made it seem as though they were in Chicago listening and watching in person.
The Democrat was declared the winner by The Associated Press as soon as polls closed.
The 21-year-old man was charged with murder and assault after his father was found dead from a gunshot wound to the head and his stepmother was also found shot.
Ryan Seeler, 34, was convicted Monday night in the July 7, 2007, death of 22-year-old Gavin Donahue, who was hit while working on a construction crew along Highway 40 near Chesterfield.