In New York, it is illegal for an adult (someone 18 or older) to have sex with a minor (someone younger than 17), even if the sex is consensual.

Can a 16 year old and 18 year old date in the US?

No this is not illegal. Simply dating a person over age 18 is not illegal. It can become illegal for a person who is 18 once sex is involved. But the situation you describe is not illegal.

Can an 18 year old and 16 year old be together?

While in many circumstances it is perfectly legal for an adult to have consensual sexual contact or intercourse with a 16-year-old, there are some circumstances where it is not. Most often, it comes down to the nature of the relationship between the two individuals.

Is an 18 year old allowed to date a 15?

In a Nutshell: Sex between an 18 year-old and a 15 year-old is illegal in California, meaning any touching of “private parts” of either, even with consent of both parties (and perhaps even the parents of each teenager) is illegal in California because the age of consent is 18.