Answer: what is important for commerce and free market economy is transport. Commerce requires transport. The faster the better. It can connect distant places, places difficult to access. Introducing railroads in societies following principles of free market led to intensification of capitalism. Railroads replaced older means of transport (horses) and enabled not only faster exchange of goods but also immigration/emigration, pollution both in Europe and USA.
Explanation: railroads were built first in the UK, later in European continent and in the North America and British colonies. It accelerated process of colonization and globalization.
