Salt Lake City is about 1.3 times smaller than Las Vegas.

Las Vegas (map shows its 26 named neighbourhoods; the area covers the whole city) is approximately 367 sq km, while Salt Lake City is approximately 287 sq km, making Salt Lake City 78.17% the size of Las Vegas.
Tip: This to-scale comparison of Las Vegas vs. Salt Lake City uses the Mercator projection, which distorts the size of regions near the poles.
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