Singapore allows many nationalities including travelers from the US to enter the city-state without a visa. For more information if your country qualifies, see http://travel.state.gov/visa/.
Health and Safety
Singapore is an extremely safe country with very little noticeable crime. However, this doesn’t mean it is completely incident free and there are pockets that are more known for criminal activity than others. Late night gangs can be seen around district like Clarke Quay, and often target foreigners walking alone. However, this is not overly common.
Tourists always need to remember that Singapore is a strict city. Locals often call it "fine city" since there are plenty of minor offenses that incur huge fees. Littering, spitting, jay-walking, and consumption of food or drinks on public transportation will get you a ticket, but they are not always policed intensely. Still, it is not uncommon for tourists to be handed down fines for breaching these laws. When it comes to drugs, the penalty is death, carried out shortly after sentencing so don't risk it.
Due to the intense heat and humidity, travelers in Singapore will need to rehydrate regularly. Sightseeing can be extremely draining because of the high temperatures and climate, so always schedule time to rest and rejuvenate.