San Marino
about 0.3 times the size of Washington, DC

Sao Tome and Principe
more than five times the size of Washington, DC

Saudi Arabia
slightly more than one-fifth the size of the US

Senegal
slightly smaller than South Dakota

Serbia
slightly larger than South Carolina

Seychelles
2.5 times the size of Washington, DC

Sierra Leone
slightly smaller than South Carolina

Singapore
slightly more than 3.5 times the size of Washington, DC

Slovakia
about twice the size of New Hampshire

Slovenia
slightly smaller than New Jersey