What Does Shishim Ribo Mean?
Shishim ribo literally means six hundred thousand. The number is drawn from the encampment and travel of the Jewish people in the midbar.
Six hundred thousand in the midbar
Shishim ribo means six hundred thousand, corresponding to the number of adult Jewish men counted in the midbar. The encampment and its public roads supply the model from which this condition enters the laws of reshus harabim.
Many Rishonim require comparable public use before a street receives the full Torah status. Other Rishonim define reshus harabim through its physical form and public access without making this number essential.
What must reach the number
Even among the views that require shishim ribo, the application is not expressed in one universally accepted formula. The discussion may focus on a particular road, the city and the roads serving it, regular daily passage, or the public population using the network.
That difference can change the result dramatically. Six hundred thousand residents in a connected city is not the same fact as six hundred thousand passages along one block in one day.
The psak determines which facts matter
Census totals, vehicle counts, transit entries, and estimates of pedestrian movement are useful only after the Rav has determined what halacha requires him to count.
The Crown Heights question therefore cannot be settled by placing a single population figure beside a map. The accepted halachic definition and the actual Brooklyn network must be analyzed together.