Farmers are gathering at several locations in the Netherlands tonight. In Amsterdam, for example, an estimated eleven to fifteen tractors are on Dam Square, says a police spokesperson. In Arnhem, an estimated 180 farmers are at the Gelderland provincial government building, a spokeswoman for that province said. In Groningen, about ten to fifteen tractors were parked just outside the city center on Thursday evening, a spokesperson for the municipality confirmed. The farmers have handed over a letter to the representative of the province of Groningen.