Niagara police stopped about 800 drivers during RIDE checkpoints in St. Catharines and Port Colborne yesterday.
Thirteen drivers were given breathalyzers and three were arrested for impaired driving.
A fourth driver was also issued a three day licence suspension after they provided a breath sample and it registered an "Alert".
Police say it was an extremely busy day with an influx of visitors for events like Ribfest and Canal Days.