Certainly, many cities have a wide variation in densities. Manhattan has a density of 50,000 people per square mile, but Staten Island is under 10,000 per square mile. New York City as a whole averages 23,700 per square mile. Using "places" rather than individual census tracts misses this variation.
The advantages of using places are that data are downloadable by state for all 23,435 places and that the number of places is small enough to make for reasonable computations. The numbers cited below assume that errors from variation within places will cancel one another out.
Table one shows the number of Americans living in places above a range of densities.
Table One: Number of Americans Living in Places Above Various Densities
Density in Millions Above Adjusted for Percent Above
Pop/Sq.Mi. That Density Missing Urban That Density
20,000 7.6 7.6 3.0
15,000 9.4 9.4 3.8
10,000 18.0 18.0 7.3
7,000 30.5 30.5 12.3
5,000 45.4 45.4 18.2
4,000 58.5 58.5 23.5
3,000 83.2 83.2 33.5
2,800 91.3 91.3 36.7
2,500 101.7 101.7 40.9
2,000 121.8 121.8 49.0
1,500 141.2 141.2 56.8
1,000 158.9 166.4 66.9
500 173.2 180.7 72.6
All places 179.5 187.0 75.2
All urban 187.0 187.0 75.2
All U.S. 248.7 248.7 100.0
The first thing to note is that the Census Bureau counted 187.0 million people as "urban" but only 179.5 million as living in "places." The remaining 7.5 million must live in fairly low-density areas, but since the Census Bureau generally defines "urban" as 1,000 people per square mile, I'll assume that those 7.5 million fall between 1,000 and 1,500 per square mile. The reality is many are probably below 1,000 and a few are above 1,500. The third column of data in the table includes this "adjustment."
Another 61.7 million people were counted as "rural." The densest rural areas are in Connecticut, with populations of 176 people per square mile. It is safe to say that all rural people live in densities below 500 per square mile.
Based on this, it appears that:
Only about 20 percent of all Americans live in such densities. Even Portland proper has a density of just 3,500 per square mile. The only metropolitan areas ("urbanized areas" in Census Bureau parlance) that have reached Metro's target densities today are Los Angeles, CA; Bangor, ME; Honolulu, HI; San Juan, PR; and Davis, CA.
Where do we find high densities in Oregon? Johnson City--which is nothing more than a mobile home court that incorporated as a city--is the highest density place in Oregon at 9,600 per square mile. King City and Aloha are right around Metro's goals.
My former home of Oak Grove is 4,300 per square mile, but this does not include Jennings Lodge, Oatfield, or River Road, the latter two of which are around 3,500 per square mile. Milwaukie, for those who live there, is 3,930. Of course, densities are going to be higher for pure residential areas ("bedroom suburbs") than for areas with a large commercial or industrial base such as Hillsboro (density 1,950) or Clackamas (1,230).
Table Two: The Densest Places in Oregon
Place Population Density Johnson City 586 9,610 Hazelwood 11,480 5,540 Powellhurst-Centennial 28,756 5,340 King City 2,060 5,000 Aloha 34,284 4,640 Oak Grove 12,576 4,300 Metzger 3,149 4,180 Gladstone 10,152 4,150 Rockcreek 8,282 4,100 Oak Hills 6,450 4,080 Jennings Lodge 6,530 4,020 Four Corners 12,156 4,010Those who live in Portland, therefore, can say that Metro wants to turn the entire area within the urban-growth boundary into a place nearly as dense as King City. Those who live elsewhere might want to point to San Jose, CA; St. Paul, MN; or Norfolk, VA as examples of city densities which smart growth seeks for entire urbanized areas.