Police have warned motorists to be wary of congestion on roads in North Yorkshire and Cumbria as hundreds of people make their to the event, which starts on Thursday, June 5, and runs through to Wednesday June 11.
Up to 2,000 caravans are expected at the event, with travellers visiting from across Yorkshire and beyond.
The A65 through the Yorkshire Dales is one of the busier routes.
Police have warned motorists to take care on the A685 between Kirkby Stephen and Brough as the road has become congested in the build-up to the fair.
Sergeant John Chambers said: “At this time of year there is an increased tolerance towards encampments whilst the area receives an estimated 1,400-2,000 caravans.”
Police said they had received reports about the risk of temporary camps adjacent to the busy A685.
They are advising gypsies and travellers heading to the fair to avoid this area before the road becomes overcrowded.
The event is a traditional gypsy fair, said to be the biggest in Europe.
A website for the event says that the best days for visitors to see the fair are Friday, Saturday and Sunday.
The website says: “The fair is a sight to see. It is a traditional gypsy fair, but the biggest in Europe. If you don’t like crowds you should give it a miss. People particularly enjoy sitting on the river bank and watching the horses being washed.”
It adds: “The atmosphere is one of good humoured holiday banter and people come to enjoy themselves.”
There are 11 car parks in Appleby. The event is co-ordinated by public sector agencies but it is not a licenced event and there is no set programme for anything happening.