Cleaning the Hudson

What: Contamination of the Hudson River with PCBs led to its designation as a Superfund site
When: 1970s to the present
Where: The Hudson River from Hudson Falls down to the harbor

The Low Line

What: Abandoned tracks and an unused terminal are being converted into a subterranean park.
When: 1903 to 1948, and present
Where: Lower East Side, Manhattan

Minetta Brook

What: The path of an underground creek that still runs today.
When: For much of the island’s history, until early the early 1800s
Where: In the West Village, around New York University

Lighting the Tree

What: A tradition created in the early 20th century
When: 1931 to the present
Where: 50 Street and Fifth Avenue, Manhattan

Heat Wave 1896

What: An intense heat wave killed 1,500 people and was nearly lost to history because of the paucity of records
When: 1896
Where: New York City