In Baltimore, the city I grew up in, 30% of the remaining Catholics schools are being closed. Only a handful remains in the whole metropolitan area, and it was the Plenary Council of Baltimore in 1852 that established the rule that every parish should have its parochial school.
Only 15% of the students in the Catholic schools in Baltimore City are Catholics.
In part, the racial and demographic changes of the past two generations are taking their final toll. Baltimore used to be a white, middle and working class city. Now it is a poor, black city with a few middle class neighborhoods, but the people who live downtown and around the renovated harbor do not have children.
The Catholic population has moved to the suburbs but the schools have not followed them. The archdiocese decided it was impossible to finance a Catholic school system when the religious who had staffed it were no longer available. And Catholics are having far fewer children, probably below replacement level for non-Hispanic Catholics.
Religious life in the United States is vanishing (see The Index of Leading Catholic Indicators). Some parishes pray for vocations, but the only contact that most people had with religious was in school. As the schools vanish, children have no contact with religious and therefore never even consider a religious vocation. That leads to an even lower number of religious, and so on in a downward cycle.
Some consider this situation decadence. But perhaps it is not. Religious life may have been suited to a certain phase of the history of the Church, and perhaps a Church that is 99.99% lay can be as vital as a Church in which priests and religious are the main carriers of religious tradition.
But Catholics in the United States relied upon Catholic schools, priests, and religious to transmit the faith, and nothing has replaced them. The European Catholics who constituted the bulk of the Catholic Church are either dying out or losing their faith; that group has suffered as severe a decline as the Episcopal Church has. Catholic numbers are increasing because of immigrants from Hispanic countries. But in those countries the surrounding culture carried and transmitted the faith, and that culture does not exist in the United States. The two or three hours of religious instruction a month that some Catholic children have until they are confirmed is really insufficient to form a Catholic identity.
A handful of Catholic families transmit both the culture and doctrines of Catholicism: they tend to be large, home-schooling families. The Catholic Church may end up like Judaism, with a small core of Orthodox families who produce children and an amorphous body of adherents who call themselves Catholic mainly because of lingering family traditions.