Is It Harris’ or Harris’s? Add a Walz, and It’s Even Trickier.

When Vice President Kamala Harris chose Gov. Tim Walz of Minnesota as her running mate, she put to rest weeks of speculation over the future of the Democratic ticket. But the battle over apostrophes was just getting started.

Where were voters (and journalists) supposed to place the possessive squiggle?

It all felt a bit, as some social media users described, like apostrophe hell: Would it be Ms. Harris’s and Mr. Walz’s or Ms. Harris’ and Mr. Walz’s? The Harrises and the Walzes? The Harrises’ family home and the Walzes’ family dog? It was enough to see double, made worse by the fact that stylebooks, large news organizations and grammar geeks were all split or contradicted one another.

“Anyone who tells you there are universal rules to how to add an apostrophe ending in S is either wrong or lying,” Jeffrey Barg, a grammar columnist, said. “You can’t be wrong as long as you’re consistent.”

The Associated Press Stylebook, widely considered to be the gold standard among news organizations, is clear on its rule for the possessive of singular proper names ending in S — only an apostrophe is needed (Harris’), though there are always exceptions. The New York Times, The Washington Post and The Wall Street Journal all do the opposite, opting for ’s to mark a singular possessive and a simple apostrophe for plural possessive (Harrises’ and Walzes’).

Merriam-Webster, the oldest dictionary publisher in America, splits the difference: For names ending in an S or Z sound, you can add ’s or just an apostrophe, though the dictionary says ’s is the more common choice.

“People want to know what the rules are because they want to do this correctly,” said Mr. Barg, who was raised on The A.P. stylebook. But at the same time, “you can’t impose language from the top down — it’s a bottom-up thing,” he said. “I think it’s going to be a learning experience for us as a country.”