Sustainability is a common buzz-word that can be heard daily in nearly all areas of life. We hear our friends, politicians, and the media all throwing the word around haphazardly, yet interesting many people use this same word to mean many different things. No single definition is commonly accepted by everyone and it seems everyone has their own idea of what sustainability means to them. To me, sustainability refers to the ability of people in a given area to satisfy their needs today, with out jeopardizing the needs of future generations of that area. The goal is to have healthy and successful places now, and ensure that such places will still be possible well into the future.
Sustainability is also commonly defined to include three main components: economics, environmentalism, and social justice. While I agree that all three of these aspects are important for future generations, it seems to me environmental protection is the most commonly discussed and debated issue of sustainability. I feel however, that economic sustainability is a key aspect of overall sustainability that deserves more discussion, especially in urban planning.
To begin with, economic sustainability goals compliment many other planning goals within cities and metropolitan regions. Economic sustainability in a city is achieved by evenly distributed income that is likely to continue coming into the city for the years to come. There are three main ways cities commonly maintain strong economic sustainability: through creating and maintaining high property values, lively commercial districts, and industrial areas and facilities.
High property values and economic sustainability go hand-in-hand. To foster high property values, municipalities often try to provide ample basic and reliable infrastructure such as water, sewer, electricity, and public transportation (Lecture, 11/20). By investing in basic infrastructure needs, the city is allowing for future desirable expansion. At the same time, the city is also investing in its own economic future by providing modern resources now so as to reduce future costs to the city.
Lively commercial districts are a planning goal of many communities due to the tax base and revenue they provide. As people will always have shopping needs, they will help to economically sustain a city into the future. As cities such as Curitiba, Brazil and Portland, Oregon have showed us, creating pedestrian-friendly corridors can attract business and customers, while at the same time provide a pleasant community atmosphere that planners often seek (The Road to Curitiba). 
Industrial areas are also important from both a city planner and economic sustainability standpoint. Much like commercial areas, city planners try to attract industry to their cities because industry provides tax revenue, creates jobs for residents, and also helps bring money into the city. Even in Ebenezer Howard's model Garden City, which advocated green cities, he realized the necessity for industrial areas within cities (Lecture, 11/6). Industrial areas are important for economic sustainability for the same reasons that planners desire them. They allow money to stay within the city and reduce the need of residents to purchase products and find jobs in other cities (Lecture, 11/20). 
Though economic sustainability complements many city planning goals, it can also at times contradict city planning goals. The clearest example of this is illustrated by the resource conflict. The resource conflict is the struggle created between economic development and environmental protection which can be created when planners are trying to achieve sustainable practices (Lecture, 11/27). In essence, increasing economic development often comes at the expense of environmental protection and vise versa, all the while the city is trying to maintain a balance of both. An example of this could be increasing industrial development. While this is economically good for the city, at the same time it could cause degradation in local environmental quality.
Another way in which economic sustainability can contradict city planning goals is by property conflict, which is the struggle between economic development and social equity (Lecture, 11/27). Going back to the industrial development example, this conflict could arise when industrial development occurs. While this is good for the city as a whole, it could disproportionately jeopardize the health and well-being of residents closest to the development (Lecture, 11/29). In this case, the city would not be meeting one of its goals of creating a positive environment for its residents.
There are many different ways planners can incorporate economic sustainability into their cities, many of which have already been mentioned. This includes planning for and creating reliable infrastructure, facilitating the creation and growth of commercial areas, and allowing for and encouraging industrial development. One of the easiest ways for planners to help create economic sustainability is by the use of zoning. Carefully planned zoning can help the city best utilize its land use practices to create long-term sustainability. For example, a city that is overly zoned residential is not economically sustainable. Most of the residents would have to find jobs elsewhere and the city would bring in little revenue from commercial and industrial areas.
Another way to help bring about economic sustainability is by means of regionalism. Municipalities must realize that it may be too late to plan for economic sustainability without the help and aid of neighboring cities. A clear example of this is the aerotropolis idea in metropolitan Detroit. Leaders and planners in municipalities near Metro-Airport have realized the best way to ensure economic sustainability is to work together as a region to create large scale economic endeavors (Lecture, 11/15). Whereas a single city may not be very sustainable, regions working together may better be able to create a sustainable future for that area.
Overall, economic development is just one key factor of a sustainable city. In order to truly be sustainable, cities must also create lasting environmental protection and social equity. It is unlikely that most cities will ever become 100% sustainable. Complete sustainability is an unrealistic utopian ideal. However, with a little work and careful urban planning, cities can easily take a step in the right direction.