ENVIRONMENTAL IMPACTS CALCULATOR I: When it was originally unveiled on the Sierra Club website on June 18, the "Environmental Impacts Calculator" allowed visitors to compare various factors at a user selected population density to those of what it called "Urban Efficient" and "Sprawl." The problem is that the "Urban Efficient" category was 500 housing units per acre --- 125 times the typical four to the acre suburban development. At the average US household size, this calculates to 777,000 people per square mile. This is a high enough density to accommodate all of metropolitan Tokyo's 33 million residents within a 3.7 mile (5.9 kilometer) radius of the national parliament (Diet) building. In fact, affluent populations do not live at similar densities anywhere in the world in all but the most micro of spaces (for example, some prisons have higher densities, such as the high-rise Metropolitan Corrections Center in Chicago's Loop).

ENVIRONMENTAL IMPACTS CALCULATOR II: Apparently recognizing its error when a frenzy of Internet and press reaction was generated by Wendell Cox (Demographia) and Randal O'Toole (Thoreau Institute), the Sierra Club revised the Environmental Impacts Calculator on June 20, 2001 to show lower densities and to reduce its "Efficient Urban" category by 80 percent (Chart below) to the equivalent of 155,000 per square mile. The Environmental Impacts Calculator still showed a higher density figure, called "Dense Urban," at 400 housing units to the acre, the equivalent of 622,000 per square mile. This is still a rather starkly high density, and would require expansion of the hypothetical metropolitan Tokyo radius from the Diet from 3.7 to 4.1 miles (5.9 to 6.6 kilometers). As with 777,000 per square mile, affluent populations do not live at similar densities anywhere in the world in all but the most micro of spaces (such as some prisons).

The June 20, 2001 80 percent "Urban Efficient" reduction to 100 housing units per square mile still represented extremely high density. At the equivalent of 155,000 people per square mile, this is below the most dense census tract in the United States, in New York, at 230,000 per square mile. But little of the US is at such high densities --- it is estimated that in 2000, less than three square miles of the nation's approximately 100,000 square miles of urban development is above 155,000 persons per square mile. Similarly areas of such extremely high population density are hard to find in other dense first world urban areas. The most dense arrondissement of Paris registered a population density of 105,000 in 1999.

ENVIRONMENTAL IMPACTS CALCULATOR III: Sometime before July 6, 2001, the Sierra Club must have recognized that promotion of such densities was unsustainable, and removed the revised Environmental Density Calculator from its website, with an "under construction" notice.

POLL ANNOUNCED: The "Urban-Policy" email list is sponsoring a poll to predict the highest density to be promoted in Environmental Impacts Calculator III. To participate requires joining the group, which can be accomplished through this link

SIERRA CLUB DENSITY CATEGORIES IN CONTEXT: Additional information on the Sierra Club densities categories is in the table below.