Missing Middle Housing consists of multi-unit housing types such as duplexes, fourplexes, bungalow courts, and mansion apartments that are not bigger than a large house, that are integrated throughout most walkable Pre-1940s neighborhoods, often integrated into blocks with primarily single-family homes, and that provide diverse housing choices and generate enough density to support transit and locally-serving commercial amenities. Although many of these are a common feature in pre-war building stocks, these housing types have become much less common (hence the “missing”). The term was coined by architect and urban planner Daniel Parolek, Principal and Founder of Opticos Design, Inc.