All Fermi answers
Fermi #23 · Question 3

How many intersections in Manhattan have traffic lights?

Explore the official answer and the simple reasoning behind this Fermi estimate.

3QUESTION 3 OF 3

Answer & explanation

The official answer, with Fermi’s reasoning step by step.

Answer & explanation

Official answer

2,900

signalized intersections

How to estimate it

Fermi’s official “Napkin math”

No single number to grab, so use the grid. The streets run up past 200th, and there are about a dozen avenues crossing them. Most of those corners have a light.

Cross streets
~220
Avenues across
× 12
220 × 12
≈ 2,600

Rounded assumptions may give a slightly different estimate. The official answer above is the game’s reference value.

Source calculation & reference
NYC signalized intersections (DOT, 2022)
≈ 13,540
Manhattan share
~21%
Manhattan total
≈ 2,900

Reference cited by Fermi: NYC Department of Transportation (2022: 13,543 signalized intersections citywide, 2,862 of them in Manhattan)

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