Jersey City is about 11 times smaller than Vienna.

Vienna is approximately 415 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 9.21% the size of Vienna.
Tip: This to-scale comparison of Vienna vs. Jersey City uses the Mercator projection, which distorts the size of regions near the poles.
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