An enduring folk apologetic for 19th century plural marriage has been to assert that it was justified because a shortage of men. Looking at raw Census data, John Widtsoe  debunked that notion, but did not end its popular appeal. Widtsoe’s conclusions have been embraced by critics  who wish to create cognitive dissonance for members who may have put too much weight on that folk rationale for plural marriage. On the other end of the spectrum, Brian C. Hales , a speaker at this year’s FAIR conference, also dismissed the folk apologetic and concentrated on rebutting critics’ plural marriage rationale (primarily as lust fulfillment) and supporting theological rationales (primarily as part of the restoration and preparation for conditions in the next life).
On a popular level, the folk apologetic has been accompanied by misleading statistics that downplay the rates at which plural marriage was practiced. A corrected ballpark figure has 15-20% of married Mormon men engaged in the practice during the Deseret era. Speculation runs rampant that a shortage of males was created by persecution caused deaths. However, such casualties were more likely to because of forced winter marches and hence not skewed towards one of the genders.
Despite these shortcomings and dismissal by many who consider themselves properly informed, it turns out that the original assertion is correct. There was a shortage of Mormon men! I will not only establish that below, but I will also advance two solid hypotheses on why the shortage existed.
In an earlier essay, I took a shot at explaining the lack of a “lost boys” phenomenon in 19th century Utah. Looking at the 1880 Census data, I found that Utah women were being married much more efficiently than their US peers, while Utah men eventually married at about the same rate as their US peers. Utah demographics were found to support high rates of plural marriage for men because 1) Utah women were married efficiently, 2) Utah had a relatively high rate of natural increase creating a wide population pyramid, and 3) under these Utah conditions, increasing the age gap between spouses created an artificial surplus of women.
That analysis likewise presents a rationale for suspending plural marriage. In today’s world we observe increased life expectancies, delayed entry into marriage to pursue educational opportunities, greater economic independence for women, large age gaps between couples becoming less acceptable, and less importance placed on having large families. Of course, whether in 19th century or now, it is necessary for a polygamous community to isolate itself from the dominant values of its ambient society. However, inasmuch as Mormon fundamentalists practice arranged marriages and outcast young single men to sustain plural marriage, they appear be addressing a shortage of female marriage partners on levels that their Deseret era predecessors did not.
In my zeal to refute old anti-Mormon accusations that Deseret era missionaries specifically targeted female converts to bring them captive to polygamous harems in Utah, I resisted the notion that missionary work facilitated polygamy. I reasoned that converts would be equally male and female and that older couples would not contribute to natural increase as much as, say, a second generation Mormon. Subsequent investigation of statistics such as those tabulated below shows that a significant surplus of women emigrated to Utah as the fruits of missionary, but their presence is masked the presence of non-Mormons (a small ~20% of the population with a large marriage-aged male disparity ) and the rising second generation of Mormons (birth rates make a large % of the population and slightly favor males).
Table 1. Sex Ratios and Marriage Statistics 
|SR||PMASR||SPMASR||SMAM (M)||SMAM (F)||Never Married (M)||Never Married (F)|
|MS (-UT-NM) 1880||209%||239%||294%||31.0||21.1||33.2%||3.8%|
In the first column of the table, overall sex ratios SR are reported. For example, there were roughly 104 males for every 100 females in the US in 1880. The sex ratio at birth has historically ranged from 102-106 . However, other factors besides native births contribute to the overall sex ratio. For regions in the US, migration played a significant role. Horace Greeley’s admonish “Go west, young man” appropriately captures the demographic of a migrating individual. There was more than 2:1 male to female ratio in the frontier mountain states (NM had been settled a while longer and was thus more family friendly).
The second column uses Kathryn Daynes’s range for prime marrying age sex ratio (PMASR) of 15-29. She found that PMASR was generally more favorable towards women in 1860, 1870, and 1880 census years (93, 100, 105) than the overall sex ratio (101, 99, 107) . As a slight refinement, I calculated a staggered prime marrying age sex ratio (SPMASR) as well: (86, 86, 90). SPMASR compares the number of males aged 20-34 to females aged 15-29 . This helps capture the five year difference in male and female ages at first marriage (estimated in the 4th and 5th column by the singulate mean age at marriage (SMAM )). Finally I calculated the SR (96, 97, 101) and PMASR (87, 94, 100) for foreign borns  in Utah for comparison with my classification of almost 90,000 names in the Mormon Immigration Index CD.
The adoption of plural marriage prevented a disaster. As seen above, a moderate surplus of Mormon women and an overwhelming surplus of non-Mormon men would have made large numbers of inter-religious marriages virtually inevitable. For some Mormon females, plural marriage was a much better option than remaining single for life (like many of their west European peers did) or marrying outside her faith. Interfaith marriages, like other assimilating influences, were important to avoid while young Mormon religious community tried to establish its own identity.
The surplus of Mormon women was the fruits of missionary work, especially in western Europe. The pre-dominance of women in the Mormon Immigration Index can be explained by a combination of two hypotheses.
1. The demographics of converts will match the demographics of their ambient society.
2. Women join new, charismatic religious movements in disproportionate numbers.
While the 1st hypothesis is a default assumption, the 2nd hypothesis was presented by none other than Rodney Stark . He wrote:
The ancient sources and modern historians agree that primary conversion to Christianity was far more prevalent among females than among males. Moreover, this appears to be typical of new religious movements in recent times. By examining manuscript census returns for the latter half of the nineteenth century, Bainbridge (1982) found that approximately two-thirds of the Shakers were female. Data on religious movements included in the 1926 census of religious bodies show that 75 percent of Christian Scientists were women, as were more than 60 percent of Theosophists, Swedenborgians, and Spiritualists (Stark and Bainbridge 1985). The same is true of the immense wave of Protestant conversions taking place in Latin America.
As judged by Mormon Immigration Index results, western Europe convert sex ratios take on an intermediate value between their ambient countries (represented by Sweden and England in the table above) and the lofty numbers Stark collected for other religious movements. Mormon missionaries were instructed to let God select the elect and warned about specifically targeting attractive on at least one occasion. One might speculate that plural marriage diminished some enthusiasm among European women to convert to Mormonism. If greater numbers of women had converted without plural marriage, it would have been very difficult to accommodate them in harsh, frontier Utah.
In conclusion, a Mormon male shortage in Utah in consistent with the 1) the assumption that non-Mormon demographics in Utah follow that found in other frontier western states and 2) foreign converts contributed a significant amount to Mormon demographics and were moderately stacked towards women. The Deseret Saints believed that plural marriage was commanded by God, while not fully comprehending the reasons why. Even if it is stretch to argue that divine foresight anticipated and prepared for frontier conditions in the Kirtland era, providing for the spiritual and physical welfare of the surplus female converts at least seems like a positive side effect.
 John Widtsoe wrote in Evidences and Reconciliations: “Plural marriage has been a subject of wide and frequent comment. Members of the Church unfamiliar with its history, and many non-members, have set up fallacious reasons for the origin of this system of marriage among the Latter-day Saints.
“The most common of these conjectures is that the Church, through plural marriage, sought to provide husbands for its large surplus of female members. The implied assumption in this theory, that there have been more female than male members in the Church, is not supported by existing evidence. On the contrary, there seem always to have been more males than females in the Church. Families — father, mother, and children — have most commonly joined the Church. Of course, many single women have become converts, but also many single men.
“The United States census records from 1850 to 1940, and all available Church records, uniformly show a preponderance of males in Utah, and in the Church. Indeed, the excess in Utah has usually been larger than for the whole United States, as would be expected in a pioneer state. The births within the Church obey the usual population law — a slight excess of males. Orson Pratt, writing in 1853 from direct knowledge of Utah conditions, when the excess of females was supposedly the highest, declares against the opinion that females outnumbered the males in Utah. (The Seer, p. 110) The theory that plural marriage was a consequence of a surplus of female Church members fails from lack of evidence.”
 I am looking in your direction, i4m.com
 I highly recommend Hales’s website http://www.josephsmithspolygamy.com/ to my readers.
 Dean May estimated 21% of Utah’s 1880 census population was non-Mormon Dean L. May, “A Demographic Portrait of the Mormons, 1830-1980,” in After 150 Years: The Latter-day Saints in Sesquicentennial Perspective, edited by Thomas G.”Alexander and Jessie L. Embry, Charles Redd Monographs in Western History No.”13 (Midvale, Utah: Signature Books for Charles Redd Center for Western Studies) p. 51, 67 cited in Kathryn Daynes, “Single Men in Polygamous Society: Male Marriage Patterns in Manti, Utah” in Journal of Mormon History 24 (Spring 1998), p. 89-111
 The tabulated values for US, Utah, and Mountain States sex ratios come from Volume 1. Statistics of the Population of the United States available at http://www.census.gov/prod/www/abs/decennial/1880.html . For the same areas SMAM and never married % come from IPUMS. For Sweden sex ratios come from data provided by http://www.scb.se/Pages/ProductTables____25809.aspx, while ancestry.com was used to extract the same for England. SMAMs for the two countries provided by Michael R. Haines, “Long Term Marriage Patterns in the United States from Colonial Times to the Present,” National Bureau of Economic Research (Cambridge, MA), NBER Working Paper Series, (Historical Paper No. 80. 1996):15-39. Guinanne, Timothy W., 1997, The Vanishing Irish: Household Migration and the rural Economy in Ireland,1850-1914. Princeton University Press, Princeton NJ. p. 96. Sex ratios for Mormon immigrants used the Mormon Immigration Index CD and relied on sites like nordicnames.com to classify gender.
 by Lee L. Bean, Geraldine P. Mineau, Douglas L. Anderton , Fertility Change on the American Frontier: Adaptation and Innovation p. 79 This fact suggests caution against the folk wisdom that women will out-number men in the Celestial Kingdom thus justifying a rationale for widespread polygamy in the afterlife. For a more devastating critique, see Valerie Hudson Cassler, “Polygamy” SquareTwo 3:1 (2010)
 Daynes also finds evidence for a surplus of Mormon women in the predominantly Mormon community of Manti PMASR (84, 81, 89) and in endowment records (77, 73, 83)
 The idea to use a staggered range for men and women occurred to me after reading Joshua Angrist, “How Do Sex Ratios Affect Marriage andLabor Markets? Evidence from America’s Second Generation” Quarterly Journal of Economics, 2002, v107(3,Aug) . Angrist uses a more appropriate range for the early 20th Century with a smaller SMAM gap (men: 20-35, female: 18-33). I used ancestry.com’s census search capabilities to break down Utah’s population by sex and age.
 I again used ancestry.com and estimated the number of foreign-born by subtract US-born from the total. However this classifies unrecorded birthplaces as foreign which makes my estimates on the conservative side. In 1860, Utah territory included counties that were later annexed to Nevada (Carson, St. Mary’s, and Humboldt) and Wyoming (Green River) that I eliminated. However, I did not eliminate counties that straddled later state boundaries. This means that Utah’s actual sex ratios are slightly lower than the figures I provide, but probably not more than 1%.
 Rodney Stark, “Reconstructing the rise of Christianity: The role of women” Sociology of Religion. Fall 1995. Vol. 56, Iss. 3, p. 229