Robert D. Putnam and David E. Campbell show that Mormons are less likely to marry outside of the faith.
Robert D. Putnam, David E. Campbell, American Grace: How Religion Divides and Unites Us (New York: Simon & Schuster, 2010), 155-156
Figure 5.7 shows that Mormons, Jews, evangelicals, Black Protestants, and Latino Catholics remain more insistent on their children marrying inside the faith than other Americans.
. . . .Turning next to evidence on actual intermarriage rates, Figure 5.8 (which does not control for opportunity and includes all American adults in 2006). . . .provide[s] relevant evidence. Figure 5.8 shows separate bars for marriages between people who are currently in different religious traditions and for marriages in which the spouses came originally from different religious traditions, with the difference between the two representing conversion by one or both partners.
As Figure 5.8 shows, intermarriage is rarer among Latino Catholics, Black Protestants, and Mormons, but intermarriage is common in all other religious traditions.