Category Archives: research

Fires of Philadelphia correction: John Colahan’s marriage

On this July 7 (the anniversary of the Battle of Southwark, 1844), I confess to an error on page 222 of The Fires of Philadelphia. 

Introducing Captain John Colahan, I wrote that in 1844 he “had connections to Protestant circles, having married Mary Dorothea Zell, daughter of a prominent Quaker merchant.” I based this claim on Charles Morris, ed., Makers of Philadelphia, an Historical Work Giving Sketches of the Most Eminent Citizens of Philadelphia from the Time of William Penn to the Present Day (Philadelphia: L. R. Hamersley, 1894), 70. Morris writes, “Soon after his advent to this city [Colahan] he married Mary Dorothea, daughter of Thomas Zell,” and I took “soon after” to mean less two years after Colahan shows up in Philadelphia in 1842.

Soon after the book was published, Professor Andrew Dinan of Ave Maria University, who is writing about the Kenrick brothers, alerted me to a letter from Francis Patrick Kenrick to his brother Peter, written on July 10, 1844, and noting that Colahan was considering studying for the priesthood. This dates his marriage to some time after July 1844, though I have not pinned down the date.

I am grateful to Professor Dinan for noting this error, and I ask that if anyone else spots a mistake they alert me as he did.

Upcoming events

Mon, July 12, 2021

7:00 PM – 8:00 PM EDT at Lost City Books (virtual)

The Fires of Philadelphia by Zachary M. Schrag with guest Tyler Anbinder

Tuesday, August 3, 2021

6:00pm – 7:30pm EDT at A Novel Idea (virtual) The Fires of Philadelphia by Zachary M. Schrag, in conversation with Carly Goodman

Thursday, December 9, 2021

7pm EDT. Library Company of Philadelphia, Fireside Chats (online) Historians’ Methods and Philadelphia’s Nativist Riots

New in 2021: The Princeton Guide to Historical Research and The Fires of Philadelphia

I have two books scheduled for publication in 2021.

In April, Princeton University Press published my book, The Princeton Guide to Historical Research, a manual for writing history in the twenty-first century. Through August 31, 2021, use the code ZS30 to get a 30 percent discount. The book is also available as an ebook or an audiobook.

In June, Pegasus Books will publish The Fires of Philadelphia: Citizen-Soldiers, Nativists, and the 1844 Riots Over the Soul of a Nation, a narrative history of America’s first great urban riot.

I am grateful to all who helped bring these books into the world.

The allure of pseudonymous history

Published: “Interviewing everyman: William Sheridan Allen, Theodore Rosengarten, and the allure of pseudonymous history,” Rethinking History,

Non-paywall version for the first 50 downloads at

Accepted Manuscript version of the article, posted here per agreement with Taylor & Francis: .

Lewis Levin Wasn’t Nice

I present some of my research on Philadelphia in 1844 in Tablet Magazine:

Levin was a rabble-rouser, conspiracy theorist, bigot, and shanda fur di goyim. In an age of resurgent nativism and fake news, he is all too familiar. Yet he is also mysterious. As a newspaper editor and congressman, Levin spoke and wrote countless thousands of words against demon rum and the Catholic menace. But he offered hardly any account of his private life, leaving historians to wonder about both the facts of his biography and the sincerity of his tirades. Where did a nice Jewish boy learn so much hate?

Lewis Levin Wasn’t Nice,” Tablet Magazine, 22 October 2018.

Metro FAQ: Why doesn’t Metro have four-track routes?

Ten years ago, when Metro was still working well enough for people to wish for more, the more frequent question I got was about the lack of a Metro station in Georgetown. Now that the challenge is to keep the current system functioning, the question is why Metro has only two sets of tracks on each route, so that shutting one down for repairs causes slow service.

In my research, I found two documents that explained the decision particularly well.
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