QNSue ... In Ontario, we have somewhere between 80-100 Fairs!
They start in May though most are in late August thru to Thanksgiving, with a only couple the week after.
There used to be many more, as every community had their own Fair. For example, within 20 kms or less, I have five Fairs! And not many more kms away, several others. With the need for volunteers and fewer people interested, the high costs of making the Fairs happen, urban development encroaching, some Fairs are struggling and do not survive. For some, the development has been a blessing, as they were able to sell old fairgrounds at development values, and start fresh with new facilities.
Size wise, some are small and only a one day fair ... most weekend from Thurs or Fri thru to Sat or Sunday ... and some run for two weekends and the week in between.
The CNE I was at in August/September is 18 days and is along the waterfront right in the ♥ of Toronto, our largest city in Canada. As you can guess, it' not your typical country Fair! There is just a small portion which showcases agriculture (where I was!) as it is seen as an outreach to help the consumer understand more about where their food comes from. This same concept is at many of the Fairs, as even with them being in the countryside, there's still a huge lack of knowledge with many. After all, farmers are only 2% of the population ... so even living in the country there is often a huge education gap when it comes to farming and how our food is produced.
Now the GrandDaddy of them all is The Royal ... world class and certainly we have a huge influx of visitors from around the world. It is held on the same grounds as the CNE, though all within buildings, linked from one to the other. Many Americans come north with their stock for the show, particularly horses and dairy cattle. It's a busy time when the Country Comes to the City!
I know you have County Fairs and State Fairs ... not so much here, just that some are bigger and better, and draw a larger crowd ... or because of their size, offer more classes and events.