| Cities | Population |
| Fort Pierce | 47,297 |
| Port St. Lucie | 204,851 |
| St. Lucie Village | 590 |
| Fort Pierce North | 6,904 |
| Fort Pierce South | 5,062 |
| Hutchinson Island South | 4,846 |
| Indian River Estates | 6,220 |
| Lakewood Park | 11,323 |
| River Park | 5,222 |
According to St. Lucie County Supervisor of Elections website, registered voters as of September 10, 2020, totaled 217,666: Democratic 85,714, Republican 72,554, NPA 56,500, Other 2,898. St. Lucie County has favored the Democratic Party in recent decades, but in 2016 and 2020, it voted for Republican Party candidate Donald Trump.
