Catholic demographics in the US, present and future:

Catholic Latinos will likely increase to 40 million in 2025, more than triple the 13 million in 1990. Total growth in the U.S. Catholic population will amount to 29 million by 2025. Virtually all of the growth (26 million) will be due to the Hispanic population. Proportionally, their share of the Catholic population will double, to 48%, over the 35-year period.

Looking back in history, the study noted that in 1790 the Catholic population of 35,000 amounted to only 1.1% of a total U.S. population of 3.2 million. A big increase took place in the 19th century. The number of Catholics increased from 195,000, or 2.5% of the total population, in 1820 to 19.8 million, 18.6% of the total, in 1920.

As immigration fell in the following decades, Catholics declined as a proportion of the population, from 18.6% in 1920 to 15.1% by 1950. In the postwar baby boom their share rose to 21.9% of the population by 1960.

I found this to be the most intriguing tidbit in the story:

The numbers of Catholics in California will have risen from 7.3 million in 1990 to a projected 16.7 million by 2025. Church membership will grow by 9.4 million, or 129%, between now and 2025. Thus, Catholics could reach 36% of the state’s population by 2025, compared with 24% in 1990. One American Catholic in five will live in California by 2025.

The growth so far has taken place within the existing structures. The Catholic Church in California added a net total of only three additional parishes between 1990 and 2005. Since the number of Catholics increased by 3.8 million for the same period, membership in an average parish grew to 10,384 from 6,854. The study cited research indicating that Mass attendance has stabilized at about 33% over the past five years (attendance was 43% in 1990).

There’s the definition of "food for thought" for you: There are 3.8 million more Catholics in CA since 1990, but there’s been an net increase of only 3 parishes. The article states outright that part of the impact lies in exponentially larger parishes, but when you look at the Mass attendance stats, you see why they’re not having to dedicate a new parish every week out there in CA.