Jill Lepore is a Harvard historian, New Yorker writer, and prolific author.
Her most recent book, These Truths,, is an ambitious attempt at a one-volume history of the US. (I wrote she is prolific, so prolific that she has another book out this year.)
I've just completed her section on the Constitutional Convention, in which I found the error. Discussing the conflict over the treatment of slaves, as persons deserving representation or as property supporting taxation, she writes: "The convention was very nearly at an impasse, broken only by a deal involving the Northwest Territory--a Northwest Ordinance...[prohibiting slavery north of the Ohio and not south] This measure passed on July 13. Four days later, the convention adopted...the Connecticut Compromise [the 3/5 count for both representation and taxation]."
What's wrong here? All the facts are right, so maybe "wrong" is too strong. But the implication, and I suggest the meaning people will take from the passage, is that the Constitutional Convention passed the Northwest Ordinance. Not so--Congress operating under the Articles of Confederation enacted the Ordinance. Because both bodies were meeting in Philadelphia the passage of the Ordinance may have been relevant to the proceedings in the convention,