| Introduction | Historical Background | Chronology | Geography | Biography | Technology | Ownership and Financing | General Bibliography |
| Northwestern States |
The following table showing the number of communities with operating systems. Numbers in parentheses indicates the number of systems that were proposed but not constructed.
| Northwestern |
1795 |
1800 | 1805 |
1810 | 1815 |
1820 | 1825 |
1830 | 1835 |
1840 | 1845 |
1850 | 1855 |
1860 | 1865 |
1870 |
1875 |
1880 |
| Iowa |
0 | 0 |
0 | 0 |
0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 7 | 17 |
| Minnesota |
0 | 0 |
0 | 0 |
0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2 | 2 | 5 |
| Kansas |
0 | 0 | 0 | 0 |
0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 (1) | 1 | 10 | 2 | 4 |
| Nebraska |
0 | 0 |
0 | 0 |
0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 (3) | 0 | 0 | 0 | 0 |
| South Dakota |
0 | 0 |
0 | 0 |
0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| North Dakota |
0 | 0 |
0 | 0 |
0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| Wyoming |
0 | 0 |
0 | 0 |
0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 2 | 3 |
| Montana |
0 | 0 |
0 | 0 |
0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2 | 2 | 2 | 2 |
| Total |
0 |
0 |
0 |
0 |
0 |
0 | 0 |
0 | 0 |
0 | 0 |
0 |
0 |
0 (4) | 3 |
6 |
15 |
33 |
© 2015-2021 Morris A. Pierce