Thornhill has a consistent population, and is popular with people in their 20s, people in their 40s, people in their 50s, and people in their 60s. Thornhill is in the southwest corner of Markham, bordered by Yonge St on the west, Bayview Ave on the east, the railway line north of Doncaster Ave to the south, and the East Don River to the north. The area to the north is parkland and trails, and the neighbourhood itself features plenty of parkland, natural areas and woodlands, as well as part of a golf course, and the historic Thornhill cemetery. Housing in this predominantly residential area is mixed, with mostly single-detached homes in varying sizes and styles, and including some mansion-like homes, as well as high-rise and low-rise multi-unit buildings, and townhome complexes. A commercial area lies near the Yonge St and Glen Cameron Rd intersection.
Families with kids make up 47% of households in Thornhill , while couples without children make up 22% of households and 26% of households are one person living alone. People in this neighbourhood come from 90 different ethnic origins, and 58% are first-generation immigrants, while 24% are second-generation immigrants.