I’m happy that we get to stay in Philly!

Thank you John!

Thanks!

Thank you, and I agree with you very much!

I'm very excited to share that I will start as Assistant Professor of Economics at @swarthmorecollege.bsky.social next fall! I cannot wait to get started!

In case you missed it last week, here's my JMP 🧵👇

Thank you Paul!

Danielle Graves Williamson

(one of my students and a stunningly original scholar in history/labor, studying "segregation academies" in the US Deep South)

bsky.app/profile/dani...

👋 I'm Danielle, and I'm on the #econjobmarket this year!

Let's start with a student describing her segregated school:

"The school felt temporary. Built like a warehouse with aluminum siding . . . I had a slipshod education"

The twist? The student is white, and her school is private.

A JMP 🧵 -->

Pier Paolo Creanza Welcome! I am a PhD candidate in Economics at Princeton University, affiliated with the Industrial Relations Section. My research focuses on topics in innovation and economic history, at the intersec...

Thanks for reading!

📄 Full paper 👉 [pierpaolocreanza.github.io/website/creanza_jmp.pdf]

📧 pcreanza@princeton.edu

👨🏻‍💻 Website 👉 www.ppcreanza.com
#EconTwitter #EconJobMarket #Innovation #EconHist (13/13)

TL;DR 🧠

💡The Great Merger Wave transformed America’s largest firms into Factories of Ideas. 💡

This paper provides the first quantitative study of the GMW’s impact. Innovation effects were large but uneven—especially strong in science-based fields requiring major R&D investment. (12/13)

This helps explain how the U.S. entered its Golden Age of Innovation (1900–1940), and why corporate labs like DuPont’s and Bell’s became national assets.

It also offers nuanced perspective for today’s debates on Big Tech and innovation. 💻🤖(11/13)

👉🏻Big firms can push the frontier but may crowd out others in well-trodden fields.

NB: Before WW2, public science was weak: federal R&D funding minimal, universities lagged Europe.

Big firms were often the only institutions able to sustain long-term R&D. (10/13)

Did these firm-level gains translate into overall progress? Yes, but unevenly. 📈 📉

Across technological domains (1905–1940):
🔹 Breakthroughs ↑ 13 % overall
🔹 Science-based fields (chemistry, electronics, telecom) ↑ 30 %
🔹 Non-science-based fields ↓ 7 %

(9/13)

I find that:

1️⃣ Firm effects matter greatly in explaining inventive productivity
2️⃣ Lab firms perform better, net of sorting and size/field controls
3️⃣ Joining a lab raises within-inventor productivity
4️⃣ Opening a lab raises firm productivity

(8/13)

Why these surges? Because mergers gave firms resources to organize research systematically. 🔬

R&D labs spread rapidly after consolidation. Lab-owning firms were substantially more innovative than others.

I use an inventor–firm panel and AKM framework to dig deeper. (7/13)

🚩 Main finding #1: Consolidation strongly raised innovation for merging firms.

Among firms that were already patenting before 1895:
🔹 + 6 patents per year (≈ 4× increase)
🔹 + 0.6 breakthroughs per year (≈ 6× increase)

Firms that had never patented became 23 pp more likely to start. (6/13)

My analysis combines three approaches:
1️⃣ Firm-level DiD → effect of consolidation on innovation
2️⃣ Inventor–firm AKM model → mechanism through R&D labs
3️⃣ Technology-level DiD → aggregate impact across fields (5/13)

To study the GMW, I digitized handwritten merger records from Ralph Nelson (1959) and disambiguated firms and inventors in the patent data (1875–1955).

This new dataset links 137,000 firm patent assignees, and 1 million inventors—the first inventor–firm panel before 1940. (4/13)

Why is this question so hard to answer?

Because firms rarely become big for reasons unrelated to innovation.

But here, mergers were driven by a deflationary Depression and a legal loophole. Corporate R&D was only nascent.

→ Firms merged to survive, not to innovate. (3/13)

The largest M&A event in US history opened an era of bigness in American industry 🏭

At the same time, the US entered a golden age of technological innovation 💡

Were these two developments connected? Many influential narratives argue they were, from Chandler to DeLong. (2/13)

🚀 I'm on the #EconSky Job Market!

My JMP asks a classic question:
Do large, dominant firms foster or hinder innovation?

To study this, I turn to the Great Merger Wave (1895–1904), when >2,600 U.S. firms combined into corporate giants like U.S. Steel and DuPont.

A JMP 🧵👇 (1/13)

From a new paper by @mjdcurtis.bsky.social, David de la Croix, et al. The Little Divergence in 'academic human capital' (kind of publications index) btw northern & southern Europe started ca 1500. Northern Germany diverged from central & southern German areas after the Thirty Years' War.

Wars were mostly bad for European economic development. Might be obvious to ordinary people, but it's not considered obvious in economic history. But I think it's obvious ;-)

Below from @sheilaghogilvie.bsky.social

Getting vaccinated is unpleasant. Dying of measles is worse. In the decade before the 1963 vaccine for measles emerged, an average of 475 Americans died from measles every year, most of them children. This (absolute) number had dropped to a low of 1 in 1981, despite a steadily increasing population that might have hypothetically contributed additional cases. Sadly, the number of measles cases in the United States has been steadily climbing upward again because we seem not to remember the ravages of the disease so much as the inconvenience of the shot—even without taking into account the absurd rejection of the solid scientific evidence in favor of vaccinations. Many people still have an elderly relative who survived a bout of severe childhood illness; not one of us has an elderly relative who did not. The blurring of the historical evidence for and against vaccination that arises from strangely incongruous historical narratives allows a seemingly inconsequential but nonetheless deadly nostalgia to run rampant.

Another example of dangerous reverence for the past concerns the flurry of popular enthusiasm lately (at least if the pundits of the 2016 American election are to be believed) for the “good old days” of the 1950s when a family could live securely on just one income (in these nostalgic accounts, that one income is usually a man’s). Lest we forget, these are the same good old days of poor air quality and measles. Maybe trivial in comparison but certainly indicative of the scope of the cognitive problem that nostalgia presents, the average size of a new home built in America in 1950 was 983 sq. ft.; by 2010, the average size had risen to 2,392 sq. ft. Given that families were larger on average in the 1950s than they were in 2010, per capita space allocation had risen even faster than total area. Although we might not need that much personal space, many of us have become used to it. Older furniture now looks tiny compared to what is now on offer in showrooms, whereas older television sets were behemoths with miniscule screens showing programs in glorious black and white.

Good history helps us avoid nostalgia. The great article “Economic History and the Historians” (2020) by Anne McCants reminds me why nostalgia can get us in trouble. Two of her examples are very relevant to today: vaccinations and the popular narrative of some economic “good old days.”

By all indications, last years economics job market was much tougher than any year since the pandemic. But all signs point towards an even worse job market coming up this season.

Let me explain.

Kenneth Sokoloff was an incredibly creative and prolific economic historian—an example anyone should be lucky to follow. Quite fittingly, innovation and business organization were one of his (many) areas of interest, and I'm proud my modest contributions build on his legacy. (2/2) #EconSky

I'm incredibly honored and grateful to have been awarded the EHA Sokoloff Dissertation Fellowship. Many thanks to the committee for supporting my research on Big Business and Innovation between 1880 and 1940.

This is particularly meaningful to me because (1/2)

Have we passed peak intelligence?

In international tests, student scores for reading and maths sunk to a new low.

US teens are struggling to concentrate & evaluate information.

The excellent @jburnmurdoch.ft.com

Warning: this thread is dark 🧵