Complex sentence: Between the late 1800s and early 1900s, there was a mass miragtion of Brienza residents to the Americas, most notably to Buenos Aires, Argentina, and Chicago, Illinois, in the United States.
Split into simpler sentences: Between the late 1800s and early 1900s, there was a mass miragtion of Brienza residents to the Americas. Most notably to Buenos Aires, Argentina and Chicago Illinois in the United States.