The appeal was launched by Cumbria Police in January to mark the 100th anniversary of female police officers.
Relatives and members of the public have dug out newspaper articles, photos and letters of 21 "pioneering" women thought to be the first to enrol.
Det Supt Cath Thundercloud said they have had a "brilliant response".
From some initial research, the force (previously Cumberland and Westmorland), believed the earliest appointment may have been Dorothy Mary Dixon, who served from January 1949 to August 1960.
However, it has now come to light that Cumbria's first female Special Constable was Mabel Farrer.
She was one of the first women appointed to the Women Police Service in 1916, training in London and then becoming one of the first female police officers in Gretna.
She went on to be Special Constable for Dumfrieshire, Cumberland, and the City of Carlisle and later Police Constable in the Northampton County Borough Police in 1918.
Ms Thundercloud said: "All the women mentioned to us were ground-breaking in their own way and we owe much to these pioneering female officers.
"We are now seeing increasing numbers of women joining the police service, which will result in a more balanced force which represents the community it serves."
Other women discovered in the appeal include Sue Pickthall, Mary Faulder, Kathleen Park and Euphemia Bennett.
Cumbria's Police and Crime Commissioner Richard Rhodes said it was "great" to hear from the families of the female police officers who played a "pivotal role" in today's workforce.
The Women Police Service was founded in 1914, and in 1915 the Grantham force swore in a Mrs Edith Smith.
Women now account for 40% of Cumbria's officers, believed to be the highest proportion in England and Wales.
The identities of Cumbria's first women police officers have been gathered following a plea to trace the county's first female recruits.