Significant Dates in Professional Soccer History
| Date | Description |
| 1967-12-07 | United Soccer Association and National Professional Soccer League merged to form North American Soccer League (NASL) |
| 1980-11-25 | Washington Diplomats (NASL) folded |
| 1980-11-25 | Houston Hurricanes (NASL) folded |
| 1980-11-25 | Rochester Lancers (NASL) folded |
| 1980-11-26 | Philadelphia Union (NASL) moved to Montreal and renamed Manic (NASL) |
| 1981-09-16 | Atlanta Chiefs (NASL) folded |
| 1981-09-16 | California Surf (NASL) folded |
| 1981-09-16 | Calgary Boomers (NASL) folded |
| 1981-09-16 | Dallas Tornado (NASL) folded |
| 1981-12-09 | Los Angeles Aztecs (NASL) folded |
| 1981-12-07 | NASL Dispersal Draft (Minnesota Kicks) |
| 2019-01-15 | Austin FC granted MLS expansion franchise |
| 2019-10-21 | Sacramento Republic admitted to MLS |
| 2021-12-14 | MLS expansion draft (Charlotte FC) |
| 2023-05-18 | MLS awards expansion franchise to San Diego (to begin play in 2025) |