North Shore Animal League America, headquartered in Port Washington, New York, is the largest no-kill animal rescue and adoption organization in the world. Since 1944, the League's mission has been saving the lives of pets through adoption, rescue, spay/neuter and advocacy initiatives. 

Each year, the League rescues, nurtures and adopts nearly 20,000 pets nationwide, and to date, has placed nearly one million puppies, kittens, cats and dogs into screened homes. One of the first animal rescue agencies on the ground in the aftermath of Hurricanes Katrina and Rita, the League rescued more than 1,400 pets from the region.


Every year the medical center takes care of more than 10,000 outpatient visits, administers more than 15,000 vaccinations and performs over 11,000 free spay/neuter procedures for adopted pets, preventing over 132 million unwanted litters. 

According to en.wikipedia