Hallee Sorenson was devastated when no one turned up to her 18th birthday party last year.
The US teen, who has autism, spent her birthday waiting at a bowling alley to celebrate with her classmates, but no one showed up.
This year, Sorenson's cousin took action to ensure her 19th birthday would not be like last year's.
Sharing a photo from Sorenson's party for one, Rebecca Guildford appealed to social media to "flood" her cousin's mailbox with birthday cards and gifts.