Elizabeth Arden, 1987

In the 1970s, photographer Neal Slavin travelled around the US documenting gatherings. From bingo players to ballroom dancers, bodybuilders to gravediggers, Star Trek conventioneers to religious congregations, Slavin photographed seemingly every imaginable organisation that humans have dreamed up. While the pictures are mostly posed, Slavin asked that his subjects arrange themselves in front of the camera, allowing natural hierarchies and indications of status to emerge. When Two Or More Are Gathered Together: 50th Anniversary Edition is published via Damiani Books

The DC Fencers Club, 1988

Says Slavin of his process: ‘I walk a delicate line between giving general instructions and allowing the group free rein to express itself while I watch individuals who jockey for position, thrusting a shoulder in front of the next person or wearing the widest smile, while others recede into the background, who are posing only to be a part of something larger – the group. My role is to capture a complete image, incorporating the eccentricities of human behaviour that have emerged naturally from the multitude of personalities’

Pugs, 1991

‘I want my work to affirm our self-identity within our public persona; to affirm the joy of being together rather than being apart,’ says Slavin. ‘My intention is to intensely glimpse that kind of human spirit through the lens of my camera.’ You can read more about this image in the Observer’s big picture feature

Grand Canyon National Park Service, 1972-75

Back in the 1970s, the National Park Service had about 250 employees, chosen from all over the country. Duties included public safety, visitor activities, maintenance and administration programmes. The Grand Canyon national park was initially established as a game preserve by President Theodore Roosevelt in 1906. Two years later he changed it to a ‘national monument’. President Woodrow Wilson established it as a national park in 1916

Cemetery Workers and Greens Attendants Union, 1972-75

The main objectives of this organisation was to seek proper wages and benefits for cemetery workers and to promote their welfare. You became a member of the union 30 days after being hired by a cemetery. The organisation was started in 1937 by workers in Greenwood Cemetery and then spread to 63 cemeteries located in New York City and New Jersey. In November 1973 president Sam Cimaglia went on a 14-day hunger strike to get a contract with the Newark Diocese Cemeteries

Star Trek Convention, 1972-75

The Star Trek Convention met each February on George Washington’s birthday weekend. The organisation wanted a film to be made and for the Star Trek television series to be brought back. The convention provided an opportunity for fans to exchange memorabilia, such as buttons, books and pictures. There was also a costume call at which they could appear as their favourite Star Trek character. The convention was started by Elyse Rosenstein and Devra Langsam in the spring of 1971 but retired after the 1976 convention was held

World Body Building Guild (WBBG), 1972-75

This international organisation met in different cities all over the world to hold bodybuilding shows and events. The purpose of the group was to promote physical fitness throughout the world and to sponsor physical-fitness contests. The organisation sponsored the following annual contests: Mr World, Pro Mr America, Miss Body Beautiful USA and Teenage Mr America. It also granted a sexiest man of the year award (Burt Reynolds and Robert Redford both won) and a sexiest woman of the century award which was given to Mae West

New York Stock Exchange, 1986

When the series was first published in 1976, it was recognised as an instant landmark in the emerging field of colour photography, which included photographers such as Stephen Shore and William Eggleston. Regarded as something of a deadpan stunt, yet framed as a serious social experiment, When Two Or More Are Gathered Together was appreciated for its surprising insights into American life

International Society of Bible Collectors, 1972-75

Organised in 1964 at Biola College and Talbot Theological Seminary in La Mirada, California, to form a fellowship for Bible collectors and to provide a journal of information concerning Bible translations. The organisation was supported by personal membership dues and library subscriptions. The Bible Collector was issued quarterly by the International Society of Bible Collectors and was the official organ of the society. No meetings were held

Cartier Inc, 1972-75

As recorded at the time, the Cartier store was renowned for its quality and special personal services. Cartier was founded in the 19th century by Louis François Cartier, who created outstanding jewellery for the courts of Louis XV and Louis XVI. In 1847 his grandson and namesake started a small factory in Paris, and soon the Cartier name spread throughout the courts of Europe. The New York firm was established in 1908 and in 1917 moved to its present quarters at Fifth Avenue and 52nd Street

The Wheelmen, 1972-75

This group met in many different states at antique bike tours, parades and meets. The object of the group was to encourage saving, restoring, riding and displaying antique bicycles; to renew America’s pride in its bicycling history; and to encourage the return of cycling to American life. Wheelmen membership was open to anyone, whether or not they were an antique bicycle owner, but members must have ridden a 10-mile tour in order to vote. The organisation also held an annual race of high wheelers on the Indianapolis Speedway

Wilhelmina Models, 1972-75

The main purpose of the organisation was to supply top-quality models to the advertising and fashion worlds. The absolute minimum height required for a Wilhelmina model was 5 ft 6½ inches. The beginning age was between 16 and 21. Open interviews were conducted Monday through Thursday for half an hour. Wilhelmina models’ activities included advertising and high-fashion magazine work, catalogue modelling, runway modelling and TV commercials

International Twins Association, 1972-75

The International Twins Convention was held annually over Labor Day weekend in various cities throughout the US. The group’s main objective was the promotion of the spiritual, intellectual and social welfare of twins throughout the world. During the convention an All Twin Judging Contest was held, with 46 trophies awarded to twins in various categories, including king twins and queen twins, oldest twins, youngest twins, most identical boy and girl twins, most identical woman and man twins, most unlike twins