Well, sometimes it did. It also shrank much faster than it does now. Under private or semi-private money, the economy tends to be much more volatile.
But on average, if you compare the two centuries, as I did using what primitive growth data we have for the 19th century, you'll see that there were spectacular years of China-style growth, but even more spectacular years of contraction. Recessions tended to be much longer, deeper, and more frequent than they are now.
But on average, the 20th century, with its Federal reserve and its fiat currency, grew not only more smoothly, but on average faster than the 19th. In 1800, real per-capita GDP was $1200 or thereabouts; at the turn of the 20th century, it was a little less than $5,000, a roughly fourfold increase. By comparison, between 1900 and 2000 real per-capita GDP went from $4,921 to $34,775, a sevenfold increase. Even if we chop off the first half of the 19th century, to put us squarely in the industrial revolution, 20th century growth still looks better. If fiat money is killing us economically, it's sure a slow-acting poison.
This article available online at: