Stock Island is an island in the lower Florida Keys immediately east of Key West separated from Key West by Cow Key Channel, which is only about 75 yards wide. Immediately northwest is Key Haven, from which it is connected by causeway with US 1. The part north of U.S. Route 1 is part of Key West city, while the southern part is a census-designated place in Monroe County, Florida, United States. The population of the CDP was 4,410 at the 2000 census. Supposedly named for herds of livestock formerly kept there. Alternatively, some local historians suggest that it may be named for an early settler. Stock Island apartments for rent comparison page shows most up to date rent information on Stock Island apartments and houses. Rent information is obtained from multiple rental sources but we cannot guarantee their accuracy.