County Clerk Thomas C. Mohr said Michael Sessions received 670 votes Tuesday to Mayor Doug Ingles' 668.
Earlier unofficial figures had shown Sessions with a 64-vote lead over the 51-year-old incumbent.
Several votes for Sessions, a write-in candidate, were disqualified because they were cast for candidates not registered to run or for candidates running for other races, the Hillsdale Daily News reported.
Because votes that the board believes were intended for Sessions must count for him, one added to his tally was a write-in reading, "18-year-old high school student."
Mohr said the two-vote lead will stand unless the count is challenged. It would make Sessions the youngest mayor in the history of Hillsdale, which has a population of 8,200.
Ingles has until 5 p.m. EST Wednesday to ask for a re-count.
Sessions used $700 from a summer job to fund his race, putting up signs throughout the city and campaigning door-to-door.
Sessions appeared on Late Night with David Letterman on Thursday to read the show's topical Top Ten list. The night's version of the feature was titled, "Good Things About Being an 18-year-old Mayor."
The list included "Parents try to tell me what to do, I raise their taxes" (No. 10), "I got a call from Demi Moore" (No. 6) and "It's flattering when President Bush calls me for advice" (No. 1).