Answer:
Hine had changed an existing cultural mindset with his photographs.
Step-by-step explanation:
The author's main purpose for including this information in the text is to show that "Hine had changed an existing cultural mindset with his photographs."
This is true because from the excerpt, it was stated that many Americans had strong anti-immigrant attitudes. But Hine's photographs on the new arrivals disproved many of the stereotype of his day. So, his photographs changed an existing cultural mindset.