According to the United States Census Bureau, the city has a total area of 99.9 km² (38.6 mi²). 97.3 km² (37.6 mi²) of it is land and 2.6 km² (1.0 mi²) of it is water. The total area is 2.59% water.
As of the census of 2000, there are 172,648 people, 67,028 households, and 39,211 families residing in the city. The population density is 1,774.8/km² (4,596.5/mi²). There are 70,723 housing units at an average density of 727.0/km² (1,882.9/mi²). The racial makeup of the city is 77.11% White, 6.89% African American, 0.45% Native American, 4.87% Asian, 0.06% Pacific Islander, 7.24% from other races, and 3.39% from two or more races. 15.15% of the population are Hispanic or Latino of any race.
The city is known for its numerous institutions of higher learning, including the University of Massachusetts Medical School, Holy Cross College, Worcester Polytechnic Institute, Assumption College, and Clark University.
There are 67,028 households out of which 29.0% have children under the age of 18 living with them, 38.3% are married couples living together, 15.6% have a female householder with no husband present, and 41.5% are non-families. 33.0% of all households are made up of individuals and 12.2% have someone living alone who is 65 years of age or older. The average household size is 2.41 and the average family size is 3.11.
In the city the population is spread out with 23.6% under the age of 18, 13.3% from 18 to 24, 30.3% from 25 to 44, 18.6% from 45 to 64, and 14.1% who are 65 years of age or older. The median age is 33 years. For every 100 females there are 92.4 males. For every 100 females age 18 and over, there are 88.7 males.
The median income for a household in the city is $35,623, and the median income for a family is $42,988. Males have a median income of $36,190 versus $28,522 for females. The per capita income for the city is $18,614. 17.9% of the population and 14.1% of families are below the poverty line. Out of the total people living in poverty, 24.6% are under the age of 18 and 11.6% are 65 or older.