It started as an impromptu family portrait in the summer of 1975. While visiting his wife's family, Nicholas Nixon asked her and her three sisters to stand together for a picture that would go on to be replicated every year for the next 40 years.
Through good times and bad, the four sisters would line up together every year for this visual documentation of their coming of age.
The first year the Brown sisters took this picture they where still attending university. It was the summer of 1975.
Taking the picture in black and white would unwittingly start a trend that would continue over the next four decades.