This is based much more on personal observation and ad-hoc local history than on any kind of formal study, but I suspect that a consistent pattern affecting Church growth in the U.S. since World War II went something like this:

Like many academically ambitious young people, significant numbers of young adult Latter-day Saints in past decades chose to pursue graduate study. In many cases, this meant dispersion from the dense LDS population centers of the Intermountain West to the major grad programs of the Midwest and the coasts. With the expansion of American universities and student-age populations in the later 20th century, opportunities for academic employment were relatively plentiful, but the geography of academic hiring also meant that most people’s careers started with a move down the prestige ladder, from large and prominent universities to smaller colleges and regional campuses.

At universities with large graduate programs, LDS students tracing this path fed the development of large wards stocked with grad student families (back in the day, our ward in Urbana, one of three family wards in close proximity to the University of Illinois, had 70 children beneath the age of 2). But there was also a high turnover rate as new students arrived to replace those who graduated and left the area.

More importantly, the next step in this career path – finding a first academic job – often led to young, stable families with substantial Church experience seeding or refreshing wards and branches in places where Church membership was low, often in smaller towns far from centers of Church membership. After investing close to a decade in starting a career path, if your one chance to continue it means accepting a job in Warrensburg, you go. And in many cases, that means you stay. Academic careers can be frustratingly static and fail to match graduate student ambitions, but people – especially those with young children in tow – also discover that there are worse things in life than a stable job in a livable town.

For seeding Church members into far-flung places, the academic path isn’t unique. There’s a parallel, sometimes overlapping path that runs through professional schools, for example. But the academic path was common enough to be a noticeable factor in wards throughout the U.S. (The population growth and economic strength of Utah in recent years has also made it much easier for successful professionals to make the return trip back to the Wasatch Front than for most academics.)

The academic path of LDS dispersion isn’t what it once was, however. The last 15 years have seen a stagnation of faculty employment, affecting the academic route for seeding wards and branches. Locally, this has meant a slowdown from a new academic family every few years, to one or two per decade. Academia has also become more overtly secular and moved farther left politically, potentially making it a less attractive career choice for LDS students, and perhaps making it less willing to welcome them, although evidence for both possibilities is scant.

It’s also possible that a contingent of LDS academics has become a vanguard of a different sort. Even with political views farther left than typical ward members, LDS academics may face higher tension between their religious and professional lives than other members, and potentially higher professional costs of church membership. Academics may be over-represented among the populations of formerly active members, families whose names are read in but never attend, and members who disappear from the ward list without any announcement that they need help moving.

If so, given the geographic structure of academic hiring, then the thumb in the eye on the way out is often delivered not to a large ward stocked with generational members like the ward they grew up in, or a ward overstocked with grad student families like the ward they attended while earning their degrees. Instead, these final wards are more likely to have immigrant, working class, and economically precarious members. The wards they leave behind never have enough people already possessing the requisite skills to staff all the teaching or leadership positions, and the number of people needing rides often outstrips the number of people who can bring them to church.