There are three types of bluebirds in the US, the Eastern, East of the Rockies and the Western and Mountain Bluebirds which are found in the Rockies and to the west. The Eastern and Western Bluebird will use a bluebird house with a 1-1/2 inch hole, while the mountain bluebird uses a 1-9/16 inch diameter entrance hole. If you use a house with too large of a hole, you may find more starlings nesting than bluebirds. Barn in the Sticks also offers several varieties of slot style bluebird houses, which have been shown to reduce sparrows nesting in your Eastern Bluebird boxes.
All of our products at Barn in the Sticks, including our bluebird houses are made in the USA.