No specific technology. My guess is that it was the instinct always to go to maximum scale. Great Britain kept much more of a small shop mindset well into the twentieth century, for instance.

My neck is too arthritic to snap around. The big shift in my perspective that happened in the writing process, however, was the paramount importance of the "West" epitomized by Cincinnati.

By 18th century standards, they [Great Britain] were the freest, most dynamic, most willing to challenge tradition and authority. They had the highest wages and highest living standard, and probably the most engagement between the populace and the government of any country. Then the United States took those same qualities to the nth degree, and the British were suddenly appeared stodgy and tradition-bound.

Whitney proved to be a competent manufacturer, but wasn't an original inventor to any important degree. Thomas Blanchard was a true genius: his stock making machine was the daddy of all the industrial profiling machinery, like the 1870s universal milling machine, that was the especial American contribution to machining technology. By that time, the British conceded that machinery innovation had shifted to America.

n truth, we don't know a whole lot of what Simeon North did. He did manage to match John Hall's ability to make interchangeable parts, but it's not clear how much of that came from Hall and how much was original with North.

I would speculate that a critical mass of the population has to internalize a middle class outlook first. International aid experience has demonstrated many times that just building railroads doesn't get you there. You need people ready to sue them.

The drive to scale in almost every endeavor. The British went very large scale in ship building and a few other industries. Their steel plants were bigger and much more advanced than ours after the Civil War, but we had blown past them by the mid-80s.