Diaries can be an amazing source for One-Place Studies and they may contain information that will not be available elsewhere. I am lucky enough to have access to a farmer's diary for my rural place in Devon, covering the period 1830-1864. There is a single line entry for each day and the weather is always noted. I can tell you how many days of rain there were during this time! There are comments about crops grown and animal husbandry, as well as accounts of chapel activities. I also have an account, written in 1870, by a young girl who was visiting the area from America. This gives descriptions of named individuals and their foibles. Finally I have been able to copy a series of scrapbooks, compiled by an elderly residents, since the 1960s. There are numerous newspaper cuttings featuring the village, photographs of many local weddings, service sheets from funerals and much more.
Wonderful though diaries are, obtaining copies of them is difficult, as they are often in private hands. if you publicise your One-Place Study widely, perhaps you will be lucky enough to be contacted by the custodian of an historic diary. Local archives or museums may have diaries. Vision of Britain at www.visionofbritain.org.uk includes searchable transcripts of many historical travel writings, including the works of William Cobbett, Celia Fiennes and Daniel Defoe. The 1870s diary that I have has been published and came up via a search for my place-name on Amazon. They are certainly worth seeking out.
Did you know that colonists settling the U.S. were required to keep a diary while aboard ship? Many continued the habit throughout their lives. A diary is a great first-hand account of what was happening in an area. Many are published and available at local and regional historical societies in the US and Canada. If your place of study is in the New England area, you may want to check the AmericanAncestors.org site. They have also published a book which is an alphabetical listing of surnames and manuscript holdings at NEHGS:
Manuscripts at the New England Historic Genealogical Society : R. Stanton Avery Special Collections / edited by Timothy G.X. Salls, Judith Lucey.
Publication Info: Boston, Mass. : New England Historic Genealogical Society, 2011.
Google.com/books is another resource for finding out information in diarists in your area. County and provincial histories are also a wealth of information.
Janet Few and Christine Sharbrough