Lucas is located in south central Collin County at 33?06?05?N 96?34?41?W. It is bordered by Fairview to the north, Allen to the west, Parker to the southwest, Wylie to the south, St. Paul to the southeast, Wylie again to the southeast, and Lavon Lake to the east.
According to the U.S. Census Bureau, the city of Lucas has a total area of 12.6 square miles (32.7 km2), of which 0.02 square miles (0.06 km2), or 0.17%, is water.
As of the 2010 census the population of Lucas was 5116.
As of the census of 2000, there were 2,890 people, 945 households, and 855 families residing in the city. The population density was 314.3 people per square mile (121.3/km2). There were 962 housing units at an average density of 104.6 per square mile (40.4/km2). The racial makeup of the city was 80.44% White, 8.42% African American, 0.52% Native American, 0.28% Asian, 0.03% Pacific Islander, 1.00% from other races, and 1.31% from two or more races. Hispanic or Latino of any race were 11.56% of the population.
There were 945 households out of which 44.9% had children under the living with them, 83.2% were married couples living together, 4.0% had a female householder with no husband present, and 9.5% were non-families. 7.5% of all households were made up of individuals and 1.8% had someone living alone who was 65 years of age or older. The average household size was 3.06 and the average family size was 3.22.
In the city, the population was spread out with 30.2% under 18, 5.3% from 18 to 24, 28.8% from 25 to 44, 29.1% from 45 to 64, and 6.6% who were 65 years of age or older. The median age was 39 years. For every 100 females, there were 98.9 males. For every 100 females age 18 and over, there were 97.9 males.
The median income for a household in the city was $100,220, and the median income for a family was $101,014. Males had a median income of $72,471 versus $38,182 for females. The per capita income for the city was $34,020. About 3.9% of families and 4.1% of the population were below the poverty line, including 3.7% of those under age 18 and 5.0% of those age 65 or over.