The online poll shows Clinton with 47.42 percent, compared to Trump's 47.38 percent, a difference of just four-hundredths of a percent.
Though the poll shows a relative tie, Clinton has regained some momentum after Trump held a slim lead for two weeks prior to Tuesday. Clinton picked up 0.41 percent from Monday's data; Trump dropped a quarter of a percentage point.
Clinton's rebound comes as the poll fully incorporates voter sentiments of her belatedly disclosed pneumonia diagnosis, which nearly caused her to faint at a Sept. 11 memorial service. Three of the seven days included in the data set released Tuesday were taken while Clinton was off the campaign trail recovering from the illness.
The UPI/CVoter online tracking poll surveys more than 200 people each day, leading to a sample size of at least 1,400 people during any seven-day span.
Because the poll is conducted online and individuals self-select to participate, a margin of error cannot be calculated. The poll has a credibility interval of 3 percentage points. This seven-day span includes data collected from Sept. 10 to 16, when 1,805 individuals were surveyed. Of them, 1,246 identified themselves as likely voters.