A complete set of 1881 Atlanta trial colour proofs is to lead a sale at Robert A Siegel in New York on September 16-17 with a $45,300 estimate.

The lot consists of 463 stamps in all denominations and colours.

Siegel states that it's "the first complete set we have offered since keeping computerized records" and describes it as "incalculably rare".

The stamps were printed for display in the 1881 Atlanta Cotton Exposition

The plates were printed for the 1881 International Cotton Exposition in Atlanta, an event held in the city's Oglethorpe Park that lasted for two and a half months and welcomed around 200,000 visitors.

It was intended to develop less wasteful methods of cotton cultivation in addition to encouraging travel to the city, which at the time was home to only 40,000 people.

The government requested the American Bank Note Company reprint five full sheets of each US stamp to date.

The huge number on offer resulted from each sheet being printed in a different colour, including the bi-colour and state department issues - which feature up to 14 colour variations.

All of the sheets were cut into blocks and singles, and sold on after the exposition.

We have a fascinating array of stamps available.

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