Brown Township, named for a Major General Jacob Brown of the War of 1812, was formed on May 3, 1815, by the Court of Quarter Sessions of the Peace of Lycoming County, Pennsylvania from parts of Mifflin and Pine Townships. Pine Creek divides the township, nearly in half and it is the center of history in Brown Township. Pine Creek was a major waterway in the settlement of north central Pennsylvania and in the lumber era that swept through Pennsylvania in the mid-to-late 19th century. Early pioneers were attracted to its remoteness and abundance of fish and game. Jacob Lamb, formerly of Milton was the first documented settler to the area. He arrived in late 1794 by paddling with his family and household supplies in ten canoes, up the West Branch Susquehanna River and Pine Creek to the mouth of Slate Run. Here, Lamb built his home. Jacob Lamb also constructed the first saw and gristmills in the area. Pioneer settler Jacob Tomb and his family established a home, sawmill, and gristmill at the mouth of Slate Run in the 1790s, and others settled nearby along the Pine Creek floodplain. By 1855, the village had a post office, general store, hotel, and two churches. Driving the local economy toward the end of the century was the James B. Weed and Company hemlock sawmill, which operated in Slate Run from 1886 to 1910 and produced up to 100,000 board feet of lumber a day. After the end of the lumber era, the mill closed, and the village declined in size. However, in the early 21st century, Slate Run still has a general store and post office, and a hotel with a restaurant and bar. Over the years Brown Township grew slowly, but it never gained a large population. It is largely a remote area, covered with mountains and a thriving second growth forest. It is popular today with outdoor recreation enthusiasts. The population was 885 by the 1890 census and declined to 111 people by the 2000 census. The Bridge in Brown Township was added to the National Register of Historic Places in 1988.
As of the census of 2000, there were 111 people, 56 households, and 38 families residing in the township. The population density was 1.5 people per square mile. There were 353 housing units at an average density of 4.8/sq mi. The racial makeup of the township was 100.00% White. There were 56 households, out of which 10.7% had children under the age of 18 living with them, 64.3% were married couples living together, and 30.4% were non-families. 26.8% of all households were made up of individuals, and 10.7% had someone living alone who was 65 years of age or older. The average household size was 1.98 and the average family size was 2.36. In the township the population was spread out, with 10.8% under the age of 18, 0.9% from 18 to 24, 16.2% from 25 to 44, 37.8% from 45 to 64, and 34.2% who were 65 years of age or older. The median age was 56 years. For every 100 females there were 122.0 males. For every 100 females age 18 and over, there were 125.0 males. The median income for a household in the township was $41,250, and the median income for a family was $55,833. Males had a median income of $24,583 versus $16,667 for females. The per capita income for the township was $22,970. There were 5.6% of families and 4.9% of the population living below the poverty line, including no under eighteens and none of those over 64.