Insightful post as always, Jim.
The 2020 proposal would reduce the "jump" limit to 1.5 miles. Currently, urban areas may jump across non-residential areas for a distance of 2.5 miles, to reflect discontinuous development along highways which are part of the urban population.
Before 2000, the jump limit was 1.5 miles, even though urban areas were defined differently. The 2.5 mile limit was adopted perhaps out of concern that an automated process might produce bunches of urban clusters that were treated as independent of the nearby city even though they functionally were not. In 2010, the Census Bureau considered a return to the 1.5 mile threshold, but the response was equivocal. It appears that the Census Bureau is simply going back to what they wanted to do in 2010.
If this rule were to get established, would it mean that we'd see some Urbanized area mergers (and thus metro area mergers as well), such as for instance San Francisco-San Jose or Los Angeles-Riverside? Those two urbanized areas already share borders with each other, but from what I know, their residential area borders are too small to classify them together.
You probably meant his part.
It is proposed that agglomerations of urban territory be merged or separated based on commuting patterns. Currently, urbanized area can absorb urban clusters, or urban clusters can merge. When two existing urbanized areas meet, they are separated at an isthmus of development or near the county line associated with their metropolitan areas.
The current separation is not based on current objective criteria, but is based on previous analysis which may not reflect current reality.
If 50% of the smaller urban areas workers work in the larger urban area, and 50% of the jobs in the smaller area are filled by workers from the larger area, the two urban areas will be merged. Essentially, the smaller area no longer maintains a separate identity.
Otherwise the boundaries can be adjusted.
If I understand the process, commuting basins are determined and smaller urban areas can be expanded to include territory commuting towards them.
Before 2000, urbanized areas were constructed and were closely associated with Metropolitan Areas. Urbanized areas started out as "Metropolitan Districts" and Metropolitan Areas were the counties around them that were economically tied to them, primarily through commuting.
In 2000, urban areas were defined based on dense residential development, and disregarded city, county, and political boundaries. It would be like looking at satellite imagery without county or other political boundaries and drawing a squiggly line around built-up areas. Urbanized areas might have grown together.
There may have been a political decision to keep existing areas. The method may be better but it it won't be accepted if it gets different results. So they maintained 1990 urbanized areas. Generally this was at or near the boundary line of the metropolitan boundary associated with the urbanized area. This resulted in boundaries near county lines.
For example, the boundary between the San Francisco-Oakland and San Jose Urbanized areas is very close to the the San Mateo-Santa Clara line and the Alameda-Santa Clara line.
The boundary between Los Angeles-Long Beach-Anaheim and Riverside-San Bernardino is east of the Los Angeles-San Bernardino county line, between Ontario and Rancho Cucamonga to the west and Fontana to the east. I don't really know why this is true. It may be due to associating Pomona and Ontario together.
This rule was preserved for 2010, though urbanized areas (greater than 50,000) were permitted to absorb urban clusters (less than 50,000).
Since the distinction between urban areas and urban cluster is proposed to be eliminated, the new rules would apply to all urban areas. A large urban area would have to prove that it had in effect captured the smaller area.
For this to happen 50% of the workers living in the smaller area would have to work in the larger area (i.e. the smaller area is a bedroom community) and 50% of the persons who work in the smaller area would come from the larger area (i.e. it doesn't even supply its own workers, it is not independent).
Otherwise the Census Bureau would use the method described in this paper to determine commuting basins.
Migration and commuting interactions fields: a new geography with community detection algorithm?Be sure to select English - but the phrasing suggest that English is a translation. But there are pretty pictures, so I think I understand the concept, if not the method.
So both SF-O and San Jose supply a majority of jobs for workers living in their respective areas, and most of their workers come from within their respective areas. In that case, the boundary between the urban areas would be modified to match commuting basins. When setting the final boundary, the boundary will be between cities.
Workers in southern San Mateo County are more oriented towards San Jose than San Francisco, so the boundary would move northward. I'm not sure about on the east side of the bay. Fremont would consider itself part of Silicon Valley, but is commuting towards San Jose? I don't know.
Vallejo Urbanized Area is adjacent to San Francisco-Oakland. This might just be a historical accident, treating Solano County as not part of the Bay Area proper. It possibly might be absorbed.
Concord Urbanized Area runs from Pittsburg down to Pleasanton. It is physically separate from San Francisco-Oakland. Livermore Urbanized Area is adjacent to the Concord Urbanized Area, so it might be absorbed into Concord. Antioch Urbanized Area exists in the extreme eastern end of Contra Costa county, but it is separate from Concord Urbanized Area.
If you think about South Florida, it is possible that separate Miami, Fort Lauderdale, and West Palm Beach commuting basins might be identified, but I don't see anything that would divide existing areas.
Because of the Everglades and the ocean, development is confined to a long narrow strip. If you could develop further west, the cities might have developed a clearer identity.
