As of the 2020 census, of there were 4,716 people and 1,849 households. The population density was . There were 2,055 housing units at an average density of . The racial makeup of the township was 80.28% White, 2.28% African American, 0.25% Asian, 3.94% from other races, and 13.25% from two or more races. Hispanic or Latino of any race were 20.12% of the population.
There were 1,849 households, out of which 22.6% had children under the age of 18 living with them, 50.2% were married couples living together, 17.5% had a female householder with no husband present while 23.5% had a male householder with no wife present, and 8.8% were non-families. The average family size was 3.24.
In the township, the population was spread out, with 25.4% being 18 or under, 3.67% from 19 to 24, 26.4% from 25 to 44, 27.0% from 45 to 64, and 17.53% who were 65 years of age or older. The median age was 40 years.
The median income for a household in the township was $68,789, and the median income for a family was $84,211. Males had a median income of $37,253 versus $25,891 for females.
Transportation
thumb|right|Carsonia Avenue in Lower Alsace Township
As of 2016, there were of public roads in Lower Alsace Township, of which were maintained by the Pennsylvania Department of Transportation (PennDOT) and were maintained by the township.
No numbered highways pass through Lower Alsace Township. Main thoroughfares in the township include Carsonia Avenue, Friedensburg Road and Antietam Road.
Gallery
<gallery>
File:Lower Alsace Twp Bldg, BerksCo PA.JPG|Township Municipal Bldg.
File:Carsonia Ave, Stony Creek Mills BerksCo PA 01.JPG|Carsonia Ave. at Stony Creek Mills.
File:Carsonia Ave, Stony Creek Mills BerksCo PA 03.JPG|Carsonia Ave. at Stony Creek Mills.
File:Fiesta Mexicana, Stony Creek Mills PA.JPG|Fiesta Mexicana.
File:William Penn Memorial Fire Tower, Reading, Pennsylvania.jpg|William Penn Memorial Fire Tower
</gallery>