[6] The town is on the northwestern border of Lewis County and lies east of Watertown.

Both New York State Route 12 and New York State Route 26 run in a northwest to southeast direction through the town, paralleling the Black River.

New York State Route 410 passes across the southeastern corner of the town.

According to the census[12] of the year 2000, there were 2,747 people, 977 households, and 753 families in the town of Denmark.

17.7% of all households were made up of singles, and 7.8% had someone living alone who was 65 years of age or older.