Margaret E. Knight was an ingenious woman. She started tinkering with things when she was still just a tiny child, and the first invention that really improved the lives of those around her came about at the age of 12.
Research:

Robert Moses and the Shaping of New York, Part 2
42:12

Robert Moses and the Shaping of New York, Part 1
41:59

SYMHC Classics: Eradication of Smallpox
43:25