Scientist and curator William Henry Pratt created this broadside in 1867, while he was living in Davenport, Iowa. It is the text of the Emancipation Proclamation, drawn to form a picture of Abraham Lincoln's face. 

After the Proclamation took effect, prints of the document were produced all over the country, and sometimes with artistic flair. This particular piece of artwork was duplicated, so a few copies exist at other institutions, such as the Library of Congress. The Minnesota Historical Society likely has a copy because Pratt lived the last years of his life here, and died in Minneapolis.