How does the Census Bureau designate these areas? In some of them, like San Diego-Chula Vista-Tijuana, the American side is dominant. In El Paso-Ciudad Juarez, they are quite balanced. In Calexico-Mexicali, the Mexican side is dominant.
Does the Census Bureau consider Calexico part of the Mexicali metropolitan area, as it exists essentially as a small American outcrop of Mexicali?
What about the Canadian ones? Detroit-Windsor and the Niagara Falls(s) for example.
It does not designate these.
I think there is some agreement between the US, Canada, and Mexico to harmonize their data collection but I don't know how far this had gone (it probably amounts to Mexico and Canada changing to meet the US).
US Data Collection is based on a nested hierarchy of:
State:County (Equivalent):Census Tract:Block Group:Census Block
Obviously these could be adapted to either country. Canada has counties, at least in some areas. But Alaska and Hawaii and Connecticut don't have counties, and they fit into the US Scheme, as does Puerto Rico.
Census Tracts and Block Groups are just statistical areas, which could be useful for reporting data within cities. The concept of census tracts originated in
1900, when the US had first begun automating its data collection and presentation. The US could produce wonder tables of citizenship and parentage for Podunk Town and at the same time with the same detail for New York City.
New York City was told that if they defined census tracts, the Census Bureau would arrange enumeration districts (areas covered by an individual enumerator going door-to-door) to match the census tracts and report data on that basis - at least to the city. They made this a general offer to other cities on a voluntary basis.
Around 1950 or 1960, the Census Bureau took over defining Census Tracts in metropolitan areas. It wasn't until 1990 that they became universal.
Perhaps the countries could agree to a common definition of the international borders. Census Coordinates are in Lat/Long and include a datum, so even if the countries used different datums they could be matched.
If there were similar data collection, some academic might define MSA's on both sides of a border and calculate population statistics. There probably is not enough commuting to truly combine MSAs, but you could certainly calculate populations for Brownsville-Matamoros, McAllen-Reynosa, Laredo-Nuevo Laredo, Eagle Pass-Piedras Negras, Del Rio-Ciudad Acuņa.
