Dorothea Lange (1895-1965) is greatest American documentary photographer, in my opinion. She is most well known for her photography from the great depression and the migrant workers. Each of these photographs of pre-WW2.
I am pretty sure this section in my history book (way back when) was the only chapter I actually read start to finish. Her photography is lovely and so subtle. Each picture captures the emotion perfectly. It makes me feel like I am standing right in front of these people.
All images taken from The History Place