Merrimack County's estimated 2026 population is 158,609 with a growth rate of 0.34% in the past year according to the most recent United States census data. Merrimack County is the 3rd largest county in New Hampshire. The 2010 population was 146,395 and has seen a growth of 8.34% since that time.
Data after 2023 is projected based on recent change
Overall: 42.9 years
Female: 43.9 years
Male: 41.8 years
There are 127,310 adults, (31,061 of whom are seniors) in Merrimack County.
Female: 78,240 (50.2%)
Male: 77,727 (49.8%)
The racial composition of Merrimack County includes 90.83% White, and smaller percentages for Black or African American, Asian, other race, Native American, Native Hawaiian or Pacific Islander and multiracial populations.
Race | Population | Percentage (of total) |
|---|---|---|
| White | 141,669 | 90.83% |
| Two or more races | 7,862 | 5.04% |
| Black or African American | 2,533 | 1.62% |
| Asian | 2,362 | 1.51% |
| Other race | 1,183 | 0.76% |
| Native American | 259 | 0.17% |
| Native Hawaiian or Pacific Islander | 99 | 0.06% |
Merrimack County's average per capita income is $59,035. Household income levels show a median of $97,004. The poverty rate stands at 7.64%.
Name | Median | Mean |
|---|---|---|
| Married Families | $132,639 | $162,004 |
| Families | $120,007 | $148,618 |
| Households | $97,004 | $123,673 |
| Non Families | $50,960 | $66,353 |
Average Income
Median Household Income
Poverty Rate