a : the difference between results obtained by observation and computation from a formula or between the mean of several observations and any of them
b : a residual product or substance
c : an internal aftereffect of experience or activity that influences later behavior; especially : a disability remaining from a disease or operation

Urban planning is an ongoing activity in virtually every community in the developed world. For the past century, urban planning has existed as a professional discipline and as an institutionalized governmental process. Much of the work that planners perform entails visioning exercises with communities to improve the places where they live, work, and play. Much of the work of planners involves the laborious technical tasks of documenting existing conditions, projecting trends, and trying to evaluate the full range of effects that would result from physical or policy changes. The work ultimately entails drafting and administering general regulations and advancing projects that shape the physical development of communities. As all this work is performed, urban planning creates its own residuals.

What does that mean, "residuals of urban planning"? I use it broadly to describe the overall effects left behind by the activity of planning, outside of the realization of the explicit plans that are adopted. This includes:

- The differences between the results of adopted plans or regulations, and the intended outcomes
- The products generated by the planning process that might be useful for other purposes (such as data that marketing firms would utilize), as well as the costs that are produced by the planning process (application fees, taxes that support planning department budgets, etc.)
- The constraints on future plans and development resulting from earlier plans
- Enduring benefits of well-planned communities after their economies have transformed from the original uses than they were planned to serve

This website is meant to broadly consider the residuals of urban planning and inspire ways to leverage them.

The transformation of the Madison Square intersections in New York City, where Broadway and Fifth Avenue run together between 23rd and 25th Streets, is one of the finest examples of creating a public place from residual space.