| Statistic | Saint-Marc-du-Lac-Long | Quebec | National |
| Population | 370 | 8,565,732 | 38,134,230 |
| Population density (sq km) | 3 | 6 | 4 |
| Median age | 55.9 | 42.6 | 40.9 |
| Male/Female ratio | 0.9:1 | 1.0:1 | 1.0:1 |
| Married couples | 57% | 50% | 66% |
| Families w/ kids at home | 31% | 40% | 43% |
| Speak English only | 0.0% | 4.7% | 68.8% |
| Speak French only | 89.0% | 49.5% | 4.5% |
| Data | Percent |
| N/A | 0.0% |
| Data | Percent |
| United States | 3.3% |
| Russia | 0.6% |
| N/A | 0.0% |