The survey found that 44% of voters support Trump, while 43% back Clinton, well within the poll's margin of error of 4.9 percentage points. Another 8% of respondents told pollsters they intend to vote for Libertarian Gary Johnson, 1% said they would write in another candidate,and the remaining 5% were undecided.
The poll is one of the first snapshot of voters in Missouri -- a state that has remained red during the past four presidential elections -- since the July conventions.
"The race was a squeaker the last time there was a vacancy in the Oval Office," Monmouth University Polling Institute director Patrick Murray said in a statement. "In that respect, this year looks more like 2008 than 2012 when Romney won the state by ten points."
The poll of 401 Missouri residents likely to vote in the 2016 election was conducted over the telephone from August 19-22.
Republican presidential candidate Mitt Romney easily carried Missouri in 2012, with John McCain clinching victory by nearly 4,000 votes in 2008 -- a year when about 3 million ballots were cast in the midwestern state.
In addition, President George W. Bush won Missouri by a margin of 7 points in 2004, despite a narrower 3-point differential four years earlier.
This latest poll found that independents were split at 40% for Trump and 35% for Clinton, with 14% supporting Johnson.
While Clinton enjoys a 65-point lead with minority voters in a state where race relations have made headlines due to the Ferguson unrest in 2014, Trump is 13 points ahead among white voters, including among white women (54% to 36%). This finding bucks a national trend for the Trump campaign, with state and national polls often showing Trump's message resonates more with male rather than female voters.
Further down the ballot, Republican Sen. Roy Blunt is 5 points ahead of his Democratic challenger, Missouri Secretary of State Jason Kander, in Blunt's bid for a second term in office. Meanwhile, Democratic Attorney General Chris Koster holds a "sizable" 11-point lead in his governor's race against political newcomer and former Navy SEAL Eric Greitens.
"Blunt is one of the first-termers that Democrats have targeted in their bid to retake the Senate," Murray said. "While he currently holds a small lead, Republican weakness elsewhere on the ballot provides the challenger with an opening."