partners of the same age will be scarce, while below-replacement fertility reduces the chance of finding a spouse among younger cohorts. Squeezed by the persistently high sex ratio and low fertility for the past 20 years, the effects will begin to show as the estimated unmarried share of 30-39 year old males will rapidly rise from near-zero today to over 20% in 2030 before receding to more moderate levels that depend on the direction of future changes in fertility and the sex ratio. The overall share of males 30+ that are unmarried will rise more steadily ─ reflecting the demographic momentum built into this open-ended age group ─ from approximately 3% in 2010 to double by 2030 and triple by 2050. Reducing the sex ratio at birth is an aggressively pursued policy solution, but it is projected to have the most significant effect when combined with increases in fertility, and only in the mid- to long-term.

As in the past, the poorer parts of China will subsidize wealthier areas demographically, with women moving from poorer areas to marry men in richer areas. We have documented that historically, women have enjoyed nearly-universal marriage and that women have selected husbands partly on the basis of wealth, and are willing to relocate to find husbands of greater wealth. We anticipate that this pattern will continue, with women leaving poorer parts of the country for the wealthier coastal and central region. Unmarried males are likely to be clustered in these poorer areas in the Southwest and Northwest, with low fiscal capacity to offer support. Guizhou is presented as an example of these areas, with 20% of males 30-39 unmarried in 2030 and up to half likely to remain unmarried by mid-century. Even controlling for education, place of residence and minority status, single men in China have lower incomes and assets and poorer self-reported health than married men. They are also less likely to co-reside with younger kin. Their vulnerability is further compounded by being clustered among the least educated, living in poorer areas, as our projections indicate. All these factors converge to raise unmarried men’s likelihood of needing support, especially in their old age, while reducing their access to support from family or the state.

People have argued that high levels of bachelorhood in China may cause social unrest, based on national averages of the problem. We show that the national averages hide a great deal, and that the problem is highly clustered geographically in the rural areas of poor provinces. Such high concentrations of men facing enforced bachelorhood and vulnerable old age could significantly increase the potential for disaffection and social unrest, perhaps even more so since many of the poorer provinces also have large populations of ethnic minorities where demographic imbalances can add to other sources of social tension.

Our conclusions are based on the assumption that the sheer numbers of surplus men ─ 27 million already born 1985-2005 ─ in China will make it difficult to resolve much of the problem through international migration. Some bachelors might emigrate to other countries, but there are practical barriers to large-scale emigration. In small rich economies, such as South Korea and Taiwan, China, foreign-born brides from poor Asian neighbors have helped mitigate the shortage of domestic-born wives. With their compact geography and high level of development, even the poorer farmers of these countries can offer good living standards and access to good schools and services. If China’s poorer provinces are able to raise their living standards quickly enough, this could be an option for some men, but the potential demand for foreign-born brides is likely to far outstrip supply in China’s setting.

For its part, Chinese policy must focus both on the short-run and long-run. Efforts to normalize the sex ratio at birth through advocacy and incentives such as the “Care for Girls” 15