As of 2010, there were 40,294 households, with 7.1% being vacant. As of 2000, 48.2% had children under the age of 18 living with them, 56.0% were married couples living together, 19.1% had a female householder with no husband present, and 19.1% were non-families. 14.3% of all households were made up of individuals and 3.3% had someone living alone who was 65 years of age or older. The average household size was 3.15 and the average family size was 3.48.
In the city the population was spread out with 31.0% under the age of 18, 8.6% from 18 to 24, 35.4% from 25 to 44, 18.7% from 45 to 64, and 6.3% who were 65 years of age or older. The median age was 32 years. For every 100 females there were 90.8 males. For every 100 females age 18 and over, there were 85.0 males.
The median income for a household in the city was $50,289, and the median income for a family was $52,952. Males had a median income of $34,145 versus $28,283 for females. The per capita income for the city was $18,462. About 7.0% of families and 8.2% of the population were below the poverty line, including 9.8% of those under age 18 and 8.5% of those age 65 or over.
As of 2000, speakers of English as their first language accounted for 60.09% of the population, while Spanish made up 29.99%, French Creole comprised 4.37%, French was at 2.13%, and Tagalog as a mother tongue was 0.50% of all residents.
As of 2000, Miramar had the fifth highest percentage of Jamaican residents in the US, with 15.4% of the populace. The fifty-eighth highest percentage of Colombian residents in the US, at 2.51% of the city's population, and the forty-eighth highest percentage of Cuban residents in the US, at 8.77% of the city's population. It also had the seventy-eighth most Dominicans in the US, at 1.98%, while it had the thirty-first highest percentage of Haitians (tied with West Little River,) at 6% of all residents. Miramar's Trinidad and Tobago community had the twelfth highest percentage of residents, which was at 1.2% (tying with Wheatley Heights, New York and Neptune City, New Jersey.)