As far as we know, the Dutch door originated in the Netherlands during the 17th century and was very popular with the settlers of Dutch and English origin who colonized what is now the United States. The door worked well to keep farm animals out of the home while keeping small children safe. The families enjoyed additional light and fresh air when the upper half was open.
One of the major advantages of the modern Dutch door is that we can keep our pets(and small children) corralled and at the same time enjoy the fresh air and view. Any time our clients express even a slight interest in a Dutch door, we design one in to the project.