Photos by National Museum of American History Courtesy of Smithsonian Institution, Currier & Ives, Dorothea Lange, and the US Army Corps of Engineers

When studying the Calumet region of Illinois and Indiana, Alfred Meyer noted four stages of development as new groups occupied this land. In stage 4, __________, new cities spread across new territory and grew toward one another.
A.
fur trading
B.
subsistence agriculture
C.
conurbanization
D.
commercial agriculture