Scottish Transport Minister Keith Brown will be in Stranraer later to launch an electric bus service linking the ferry terminal in Cairnryan with the town's railway station.
The town's west Pier will also be officially reopened.
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The first of seven races will begin at 5:45pm, and 76 horses are competing. The UK's top female jockey is amongst the competitors.
Thousands of people are expected to flock to Brampton to catch a glimpse of the colourful breed, which is more common in warmer climates.
More than 120 young athletes are taking part in this year's Borders Sport and Leisure Sports Academy.