The challenges of crunching numbers on Election Night

"All results are unofficial."

That caveat was included in every local election story we published in the April 7 edition.

And, indeed, there were scores of races that were too close to call on Election Night, for myriad reasons.

The first wrinkle: Mail-in ballots that were postmarked by April 6 had a two-week postelection window for delivery - meaning they could arrive as late as April 20 and still count.

The Northfield Township supervisor's race illustrates how fortunes can change in that span. The night of April 6, five-time incumbent Jill Brickman, a Republican, held a 56-vote lead over Democratic challenger Shiva Mohsenzadeh. But a week later, after the addition of mail-in and provisional votes, Mohsenzadeh had pulled ahead by 139 votes. The final margin of Mohsenzadeh's victory ended up being 165 votes.

Another reporting complication can arise from the clerk's offices themselves. Every year, in a bit of gallows humor, we editors speculate on which county will be the one to have a meltdown on Election Night. This year, both Lake and Cook experienced significant reporting delays.

In Lake County, some election judges couldn't upload their data from their local precincts and instead, around 9 p.m., resorted to driving to the clerk's office in Waukegan to deliver memory sticks. In Cook County, the first batch of results wasn't posted online until 9:35 p.m., a delay the clerk's office attributed to a court order that kept some polling places open an hour later than scheduled, and no referendum results were posted at all Tuesday night.

However, as McHenry County showed, speed doesn't equal accuracy. Volunteer poll watchers noticed that the tallies posted on the doors of three Cary polling places did not match what was reported online. The clerk's office discovered that changes made to ballot language shifted the spacing just enough that tabulation machines couldn't read votes correctly. Ultimately, a countywide recount was ordered, and that changed the outcome in the Huntley Community School District 158 race.

But let's also give props where props are due: The Will County clerk's office consistently has been the gold standard for quick and reliable tabulation.

The third and final variable we need to keep in mind is write-in votes, which never are available on Election Night. The smaller the community, the more likely write-in votes will determine the race.

In tiny Mettawa, which has a population of about 550, Mayor Casey Urlacher chose not to file for reelection after he was indicted in a federal gambling case. The pardon he received in the waning days of President Donald Trump's administration changed things, however, and Urlacher launched a write-in campaign against former Mayor Jess Ray.

Urlacher declared victory on April 9 after the Lake County clerk's office showed he had received 151 write-in votes to the 105 ballots cast for Ray.

• News Editor Michelle Holdway works on the night copy desk. She has been coordinating election coverage for the Daily Herald for nearly 20 years.