The story is complex. There aren't really no "gimme evidence" answers to these kinds of issues. A lot of people over centuries in many countries give you a lot

The story is complex. There aren't really no "gimme evidence" answers to these kinds of issues. A lot of people over centuries in many countries give you a lot if stories. One major factor was population growth. This was due to the coming of American crops (corn, potatoes, etc) and the green revolution (fertilizers, machinery, etc.). Another major factor (say in Ireland, where I'm from) was a change in the social-political system. There was a shift from old the old lordship order to a more modern landlord order. Relationships (rights, obligations) between lords/landlords and the landed an unlanded peasantry... Today we might call it rural unemployment and/or a small farm debt crisis. The latter half of this change is known in Ireland as "the land wars." There were also "pull" factors. These are more complicated, because they do involve choice. Cities offered a lot of hope. You might do very well in a city. Many did poorly though, and food/sanitation was often worse. A lot of the migration was (for example) adolescents sent to work as domestic servants... so thinking in terms of "homo economicus" is best tempered with some visualisations... say Oliver Twist. Similar things happen today in developing economies. Rural unemployment and stagnation. Cities that offer shiny opportunities in a game with few winners and many losers. Hence urban slums, 80 hr workweeks, etc. Working conditions in factories was also a 200+ year process. Unions played a big role. Politics played a big role. Revolutions and fear of revolutions played a big role. In Ireland, Soviet and pre-soviet revolutions were the threat that catalyzed land and labour reforma immediately before independence from the UK and after it. The Irish independence war was contemporary to the Russian Revolution, so the politics were naturally intertwined. For the most part, material conditions for the poor were a lot worse in the cities for most of the industrial era(s). Education was better and people became more worldly in cities. Rural peasantry tends to be culturally stagnant by default. Marx, in his day, saw this migration as the preceding factor to revolution. He was snobbishly dismissive of peasants' ability to evolve culturally, so revolution had to wait until a generation or two was seasoned by city life.