Jersey City is about 41 times smaller than London.

London (including the 32 boroughs of greater London) is approximately 1,572 sq km, while Jersey City (map shows its 11 named neighbourhoods; the area covers the whole city) is approximately 38 sq km, making Jersey City 2.43% the size of London.
Tip: This to-scale comparison of London vs. Jersey City uses the Mercator projection, which distorts the size of regions near the poles.
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