Congratulations to New Castle County, Delaware for going live with ProjectDox! New Castle County has the highest population and population density of any Delaware county, even though it is the smallest. It is also the most economically developed. New Castle County has a strong zoning code, known as the Unified Development Code, or UDC. The UDC was developed by the Gordon Administration in response to public perception of over- and mis- development in the county. New building projects must go through an arduous process of application and approval before construction is permitted to begin.