These are postcards of the Port Mayaca area on the east bank of Lake Okeechobee. They are undated, but likely come from the early 1930s.
The reverse of the three cards read:
“Sunset at Port Mayaca, where the St. Lucie Canal enters Lake Okeechobee.”
“The St. Lucie, Florida’s Grand Canal, which gives Port Mayaca another five miles of interesting water frontage.”
“In the pine wood at Port Mayaca near the Saint Lucie Canal.”