How close do you have to be to someone to catch strep throat? i ran into my neighbor (has strep), we were at least 15 feet apart, am i at risk??

No. Strep is spread: by physical contact( like shaking hands, etc) or eating/drinking after someone infected. It's a bacteria. Viruses are spread be coughing/sneezing, in addition to physical contact.

Saliva: You are not at risk from the contact you describe. Strep is casually passed through saliva. Since the person touches their face/nose occasionally it will end up on their hands and transiently on things they touch. The germ can live temporarily on objects you might touch & transfer back to you by reversing that process.