11 gorillas, 55 flamingos, 3 lions and thousands of hissing cockroaches: Breaking down Lincoln Park Zoo’s population

The Lincoln Park zoo celebrated its 150th anniversary, and the Chicago Tribune marked the occasion by publishing several pieces on the free city zoo’s history.

The zoo started small: two pairs of swans in 1868. (Archive link) For this piece I worked with an animal census dataset — supplied by the zoo — and visualized it using d3.js.