For this blog, it names the Roman rite churches taken together, but it is not an ecclesiological claim that they constitute a particular church of themselves. I would rather claim that they are a group of local Churches, even though neo-Yankee homogenization has created a single identity for many if not most of their members.
Rather, what is important is that the bishops (and those Roman Catholics of influence) tend to see themselves as possessing one national identity, rather than having many identities, rooted in the local political community.
(It is a reason why moving bishops around in a country as large as the United States, without expecting that the bishops would assimilate into the local society, like St. Paul and the best of Christian missionaries, was a mistake.)
"The Immigrant Church." True of Roman Catholics but also of Eastern Catholics and the Orthodox. How many of them really integrated into Anglo-Celtic-American society in the 19th and early 20th centuries? (As opposed to becoming propositional Americans who are able to speak English?)