Did technology or migration play a more important role in industrial urbanization?

The correct answer to this open question is the following.

Although there are no options attached or further references, we can say the following.

Technology and migration played an important role in industrial urbanization. However, immigration played a more important role in that immigration directly impacted the growth of the cities where major industries were located. We are talking about large cities such as Chicago and New York.

These big factories attracted thousands and thousands of immigrants, basically from Europe. Talking about the United State province, former farmers decided to leave the rural areas of the country and emigrated to the larger cities to work in the factories.

The consequence of this migration was that cities grew very fast and overcrowding became a problem. Poor immigrants lived in small places with no ventilation, unhealthy conditions, and with the risk of spreading diseases.