The Transcontinental Railroad Act is the first step in creating a continental common market.

After I finished the Tycoons - on post-Civil War development - I realized how much I didn't know about the first half of the century, even though there had obviously been an enormous amount of development, so I read about and thought about that for a couple of years before I decided I was ready for a book.

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.

It's clear that North took some original steps in that direction, but Hall probably had the most complete approach and should get the most credit. But for Hall, unfortunately, the data are all impressionistic - what people said. None of his machinery survived. His patents were all lost in the Patent Office fire.

John D. Rockefeller was certainly the first to create a consumer product that was sold literally throughout the entire world. Those blue 5-gallon cans showed up in some of the remotest parts of the world.

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.

The kind of precision manufacturing epitomized in the armories, while it was important, was only a small share of the economy until quite late in the century. Large-scale natural resource development and processing was the name of the game.