In yesterday's posting we decided (I decided, coming out from behind the editorial screen) that what Pius XI meant by the "Reign of Christ the King" is conformity of our laws and institutions (and, yes, our personal behavior) to the precepts of the natural law, chiefly through widespread capital ownership. Pius XI was not talking about the establishment of a theocracy, or even conversion of the world to Catholicism (in that encyclical, anyway). The United State government was, in this understanding, originally based on "Catholic" political theory. (To see how far we've deviated from this, take a look at William Crosskey's Politics and the Constitution in the History of the United States. Chicago, Illinois: University of Chicago Press, 1953.)
Heinrich Rommen appears to agree with this analysis in his book, "The State in Catholic Thought," although he studied Suarez more than Bellarmine. Rommen was a student of Father Heinrich Pesch, S.J., the founder of "solidarism" (at least the Christian version of it), was (with other students of Pesch) a member of the Königswinterkreis in Germany before it was suppressed by the Nazis. It was headed by Father Oswald von Nell-Breuning, S.J., who, with Father Gustav Gundlach, another member of the group, was called to Rome by Pius XI to consult on Quadragesimo Anno — of which about half talks about how important it is for ordinary people to own capital.
Blessed Pius IX also spoke well of the United States, as did Leo XIII's Apostolic Delegate, Cardinal Satolli, who declared that the Gospels of Christ and the Constitution of the United States are the Magna Charta of humanity. Leo XIII also gave a virtual endorsement of the American political system in Testem Benevolentiae Nostrae in 1899, at the same time condemning the application of democratic methods to the determination of religious doctrine and Church governance.
Leo XIII also seems to have used the U.S. as a model in writing his encyclicals (Testem Benevolentiae Nostrae is an "Apostolic Letter," not an encyclical), particularly in light of Lincoln's Homestead Act and Leo's insistence that everyone should be put in the position of being able to own capital. (In context, it is clear that Leo was using "land" in a way that includes capital, where in binary economics we include land under capital — mere semantics — besides, he specifically stated that the rights of private property apply to both landed capital and non-landed capital.)
Unfortunately, by the time Leo XIII wrote, things were already on the downturn. Rerum Novarum was written in 1891, but by 1893 at the Columbian Exposition Frederick Jackson Turner believed that the "frontier" was then effectively closed as most of the available land had been taken.
In accordance with his "frontier hypothesis," Turner believed that the end of "free" (i.e., available) land meant the end of democracy, a judgment borne out by history when land per se was not replaced with the availability of other forms of capital as, e.g., Judge Peter S. Grosscup (one of Theodore Roosevelt's "Trust Busters") recommended.