Avalon is a borough in Cape May County, New Jersey, United States. It is located on Seven Mile Island. As of the 2020 United States census, the borough's population was 1,243, a decrease of 91 (−6.8%) from the 2010 census count of 1,334, which in turn declined by 809 (−37.8%) from the 2,143 counted in the 2000 census. The borough's population swells to as many as 45,000 during the summer.