Sometimes its helpful to actually know what I'm writing about (d'oh!).
Well, they are close now, to be sure, but Mother of God Church was not a Catholic Church until about 1949, so my analysis there fell sort of flat. Of course, Holy Ghost and the Cathedral of the Immaculate Conception have always been Catholic Church's, so my analysis still made sense there.
Be that as it may, another church also provides an interesting example of changing times, that being
Holy Rosary. Holy Rosary is probably no more than five miles, maybe less, from the Cathedral, but it's north of I70, and it would be hard for people in the neighborhood to get to the Cathedral even now, so I can understand why it is there. Having said that, what surprised me is that, in reading the parish history, how ethnic it originally was.
The church, built in 1918, originally served a principally South Slavs population. Another Catholic Church existed within just a few blocks, but it was principally Polish in population. Prior to the construction of Holy Rosary, the South Slavs attended that church, but they wanted one of their own. That's probably understandable given language differences between the various parishioners. Of interest, a Russian Orthodox Church was and is located very nearby.
What all this shows is that there was a rich population of Eastern Europeans in this section of Denver early in the 20th Century. They all lived in the same area, but they also maintained certain distinctions between themselves. Overall, that's not surprising, but the degree to which the distinctions were maintained perhaps is.