I might me wrong but i think it is Spain sorry if Im wrong
Headright system allowed settlers their own land
City planners adopted railroad technology in the Industrial Age to help out commuters. Since a lot of factories were not located close to homes, people took the train to get to work as their way of transportation.
Answer: Most likely the industrial revolution.
Explanation: The use of machines in production became more and more prevalent, eventually many factories were built in cities which caused pollution therefore making the air gross.