[dotch]

It's an argument that gets made over and over again:

Paris: density 55,673/mi^2

SF: density 17,246/mi^2

(source: wikipedia)

[somberi]

To expand:

All of NYC - 28,053/mi^2 Manhattan alone - 72,033/mi^2 London - 13,410/mi^2

[lmm]

Bear in mind that's using the legal definition of Paris which excludes many of its suburbs.

[ido]

The SF definition is also excluding its suburbs (i.e. Silicon Valley).