The latest monthly voter registration figures show that, since the 2016 general election, the Secretary of State has removed 14,319 South Dakotans from the active voter registration list. Democrats have lost 10,061 voters and Republicans have lost 6,284, while the Independent/No Party Affiliation roll has gained 2,061.
| GOP | DEM | IND/NPA | Const | Lib | Other | Total | Inactive | |
| 11/08/16 | 252,115 | 170,694 | 118,669 | 500 | 1,620 | 829 | 544,428 | 50,698 |
| 12/01/16 | 253,132 | 170,671 | 119,829 | 499 | 1,644 | 840 | 546,615 | 49,615 |
| 01/03/17 | 253,619 | 170,572 | 120,638 | 501 | 1,659 | 844 | 547,833 | 49,019 |
| 02/01/17 | 253,782 | 170,387 | 121,334 | 495 | 1,661 | 846 | 548,505 | 48,638 |
| 03/01/17 | 253,854 | 170,057 | 121,711 | 495 | 1,666 | 848 | 548,631 | 48,476 |
| 04/10/17 | 253,845 | 169,688 | 122,373 | 493 | 1,682 | 843 | 548,924 | 48,141 |
| 05/01/17 | 253,983 | 169,442 | 122,806 | 494 | 1,682 | 841 | 549,248 | 48,188 |
| 06/01/17 | 254,166 | 169,240 | 123,452 | 490 | 1,686 | 837 | 549,871 | 47,985 |
| 07/05/17 | 254,569 | 169,094 | 124,260 | 489 | 1,693 | 837 | 550,942 | 35,860 |
| 08/01/17 | 253,819 | 168,257 | 124,140 | 486 | 1,701 | 834 | 549,237 | 30,619 |
| 09/01/17 | 249,085 | 163,830 | 121,641 | 475 | 1,651 | 793 | 537,475 | 42,069 |
| 10/03/17 | 247,477 | 162,482 | 120,980 | 475 | 1,671 | 789 | 533,874 | 46,511 |
| 11/01/17 | 247,267 | 162,036 | 121,572 | 474 | 1,673 | 786 | 533,808 | 47,597 |
| 12/01/17 | 245,831 | 160,633 | 120,730 | 471 | 1,662 | 782 | 530,109 | 51,795 |
| Nov–Dec | -0.58% | -0.87% | -0.69% | -0.63% | -0.66% | -0.51% | -0.69% | 8.82% |
| YTD | -3.07% | -5.83% | 0.08% | -5.99% | 0.18% | -7.35% | -3.24% | 5.66% |
| since ED | -2.49% | -5.89% | 1.74% | -5.80% | 2.59% | -5.67% | -2.63% | 2.16% |
| % of total | 46.37% | 30.30% | 22.77% | 0.09% | 0.31% | 0.15% |
The Republican share of South Dakota’s active electorate was creeping down for most of the year but picked back up once the annual voter purge took place. The percentage of Republicans on the voter rolls has thus since last Election Day just a touch, from 46.31% to 46.37%. The Democratic share over the same period declined every month, from 31.35% to 30.30%. The percentage of active voters declaring themselves independent or unaffiliated rose every month until plateauing in November, rising from 21.80% last Election Day to 22.77% yesterday.
The Libertarians have shown the largest growth rate since last Election, although in raw terms, there are only 42 more registered Libertarians in South Dakota than there were when Gary Johnson came in third in our fair state. If every party continued the same rates of growth or decline that we see above (an amusing speculation that ignores rekindled election year interest and the pendulum of history), the Libertarians would catch up with Democrats in total registered voters in 2081 and with Republicans by 2142. Of course, by then, the Libertarians would still be only 2% of an electorate that would be 96% independent.