Johnson County Precinct Results (as reported by parties; the Auditor's Office does not conduct the caucuses or tabulate results.)
- Democratic (attendance and delegate counts; the Iowa Democratic Party did not release caucus vote totals until 2020)
- Republican (attendance and vote totals)
Democratic: 18,363
Republican: 3,980
Total: 22,343
Registration and Party Change Statistics
While other registrations were processed between Jan. 3 and Jan. 16, the overwhelming majority were from the caucuses.
January 1, 2008 was the first day voters could register as Green or Libertarian under Iowa law.
| Jan. 2, 2008 - day before caucus | ||
| Democratic | 36,193 | 43.50% |
| Republican | 16,092 | 19.34% |
| Green | 1 | - |
| Libertarian | 0 | - |
| No Party | 30,920 | 37.16% |
| Total | 83,206 | |
| Jan. 16, 2008 - caucus data entry completed | ||
| Democratic | 40,431 | 47.87% |
| Republican | 16,710 | 19.79% |
| Green | 6 | 0.01% |
| Libertarian | 4 | 0.00% |
| No Party | 27,306 | 32.33% |
| Total | 84,457 | |
| change | ||
| Democratic | +4,238 | +4.37% |
| Republican | +618 | +0.45% |
| Green | +5 | - |
| Libertarian | +4 | - |
| No Party | -3,614 | -4.83% |
| Total | +1,251 |