The South Sudanese diaspora have played an important, and perhaps indispensable, role in bringing about the referendum on independence from Sudan that is taking place this week.
Having successfully obtained refugee or asylum status in the United States, Canada, Britain and some other countries, the exiled political elite from the region have pressed those governments to support the referendum process, and to recognize an independent southern Sudanese state if the referendum succeeds.
Accordingly, there was considerable debate before the voting began about whether South Sudanese living abroad — estimated by the United Nations to number between 500,000 and 2 million — or in the northern part of Sudan would be allowed to cast ballots. Northern politicians argued against letting them do so because the diaspora is regarded as quite politically active and heavily in favor of separation.
In the end, South Sudanese residing in the eight countries where the bulk of the diaspora is believed to live were allowed to register with the independent Southern Sudan Referendum Commission to cast ballots this week. The eight countries are Australia, Britain, Canada, Egypt, Ethiopia, Kenya, Uganda and the United States.
Even so, despite considerable political effort by southern politicians and western governments, only 60,000 diaspora voters actually registered, according to final figures released on Saturday by the commission — which may be as little as 4 percent of those eligible, depending on the estimate of the diaspora population you use.
South Sudanese:
| Total pop. (est.) | Voting age (est.) | Registered voters | Percent registered | |
| In South Sudan | 7.5 to 9.7 million | 3.75 to 5 million | 3,755,512 | 75% to 100% |
| In North Sudan | 1 to 2 million | 0.5 to 1 million | 116,857 | 12% to 23% |
| Diaspora | 0.5 to 2 million | 0.25 to 1.5 million | 60,219 | 4% to 24% |
| Total | 9 to 13.7 million | 4.5 to 7.5 million | 3,932,588 | 52% to 87% |
By contrast, it appears that more than 75 percent of eligible voters living in South Sudan registered, numbering nearly 3.8 million people, and some 120,000 more South Sudanese living in the North registered to vote.
Because of increased migration from north to south in the past year, it is unclear how many South Sudanese of voting age remain in the North, though we estimate here that the registered voters represent 12 to 23 percent of the total eligible population.
Under the terms of the referendum, a simple majority of the votes cast (50 percent plus 1 vote) will decide the outcome, but for the outcome to have effect, at least 60 percent of registered (rather than eligible) voters must have cast valid ballots.
Conventional wisdom holds that there is almost no support among South Sudanese for remaining united with the North. If that is true, the only conceivable way for the referendum to fail would be by falling short of the turnout requirement.
The 60 percent threshold equates to 2,359,553 valid votes that must be cast over the course of this week, a figure that could be reached easily even if a significant share of voters in the North are prevented from casting ballots (through intimidation or logistics) or if overseas turnout is low.
Turnout scenarios:
| Registered | Low Turnout | Moderate Turnout | High Turnout | |
| South Sudan | 3,755,512 | 65%: 2,441,083 | 80%: 3,004,410 | 90%: 3,379,961 |
| North Sudan | 116,857 | 20%: 23,371 | 25%: 29,214 | 50%: 58,429 |
| Diaspora | 60,219 | 25%: 15,055 | 50%: 30,109 | 75%: 45,164 |
| Total | 3,932,588 | 2,479,509 | 3,063,733 | 3,483,554 |
Starting with a turnout figure of 65 percent for South Sudan, matching that given by the National Electoral Commission for the controversial 2010 general election, we can estimate a turnout of at least 2.44 million in the region — enough to exceed the 60 percent threshold even without a single diaspora vote. If turnout is high, the referendum might clear the minimum turnout hurdle by more than a million votes.
Consequently, barring significant fraud or an enormous number of invalidated ballots, it is almost certain that the independence vote will achieve the vote totals needed to make it legally binding, and therefore send South Sudan hurtling toward statehood. And it seems that in the end, the impact of votes cast by the diaspora, as well as by voters living in Northern Sudan, will be almost negligible.
Notes on data
Follow these links for the sources of cited figures for the South Sudan population, estimates of the diaspora and the number of South Sudanese living in the North, and voter registration. For the voting-age proportion of the population, a rate of 50 percent, about average for Sub-Saharan Africa, is used. For the turnout in South Sudan in the national elections of 2010, the official 65 percent figure is used; there were claims that it was fraudulently inflated, but other reports called it fair, and no better figure is available. Diaspora voting rates in general elections in sub-Saharan Africa tend to average between 20 and 30 percent, with registration rates often below 10 percent. Given the high profile and identity associated with this referendum, and the highly publicized registration period, I use the estimates shown. For Northern Sudan, the estimates assume that some level of intimidation, logistical difficulties and fraud will inhibit an otherwise highly motivated electorate.