In 1450, the Bubonic Plague still held Europe its grasp, and continued to devastate populations of cities large and small well into the late 1500s. The total population of Europe by the end of the 1500s, when the last of the great outbreaks of Plague subsided, is estimated to have been around 25 million, down from an estimated 75 million when the Plague first arrived on merchant ships in Italian ports roughly two hundred years earlier. By 1750, however, the population of Europe had exploded back to an estimated 120 million.
In 1450, before the travels of Columbus and the Age of Exploration had gotten fully under way, the Plague had not yet been replaced by diseases such as Syphilis, which was brought back from the New World, along with new crops and animals in the so-called “Columbian Exchange.” The main crops brought back to Europe from the New World in this time period were as follows: maize (corn), tomatoes and potatoes, all three of which would become staple crops in Europe by the 1700s.
These crops changed European agriculture dramatically, because potatoes in particular became known as hardy crops that were quite resistant to the cold and to other diseases that led to crop failures. Also, because of their high starch content, potatoes could provide a great deal of sustenance on a pound for pound basis. Within a few hundred years, peasants from Ireland and England to Russia were heavily dependent on potatoes for their lives and livelihoods.
As for disease, aside from Syphilis, it was Europeans and their livestock that carried most new diseases (smallpox and measles) to the New World, and not the other way around. Europeans also brought horses, chickens, domesticated cattle, pigs, rats and sheep to the New World, while Europeans brought back far fewer species of domesticated animal from the New World. The most notable species to come to Europe from the New World were turkeys, llamas and guinea pigs. Yet these animals had a limited economic and cultural impact in Europe, particularly compared to the outsized impact that horses and cattle had in the New World.
That said, in terms of human population movements, far more Europeans moved to the New World than vice versa. For countries with limited space and high population densities, such as England and the Netherlands, North America became a destination for those seeking to advance economically in ways they could not back at home. Some select poorer Englishmen and enterprising Dutch with fewer prospects for gaining wealth and land back home sought fortunes on the Atlantic Coast of North America, and so did many Portuguese in Brazil, where growing plantations required white overlords to manage huge influxes of African and mulatto slaves.
Similarly, the slave trade on the southern Atlantic coast of North America (Virginia and the Carolinas, primarily) brought poor Scottish and Irish workers over to serve as plantation hands and slave overseers, although the overall number of Europeans who travelled to the New World by 1750 was relatively small. The vast majority remained in Europe, and of those who remained, most stayed in small towns and villages, engaged in agricultural life.
Even so, by 1750, the populations of major cities in Europe like London and Paris had eclipsed their heights reached prior to the arrival of the Plague. The estimated population of Paris in 1400 was 280,000. By 1500, because of the plague, the population had dropped to an estimated 200,000, before rebounding to above 500,000 by the 1700s. A similar pattern was at work in London, where estimates show the population growing from between 50,000 and 100,000 in 1500 to around 700,000 in 1750. Like Paris and other major port cities in Europe, London expanded in size and population over the course of those three hundred years, in large part to accommodate the growing trade with the New World.
It was not until the late 1700s and early 1800s that the Industrial Revolution, beginning first in England, began to draw vast populations of workers from rural farming villages into big cities to fill jobs in factories. In other words, by 1750, the balance of Europe’s population remained engaged in farming and skilled trades that serviced a mostly agricultural economy, despite the voyages that had brought new crops, diseases, animals and wealth across the ocean.