Construction of the Mount Pleasant meetinghouse began in 1814, with Jacob Ong serving as both architect and builder and basing the plain but massive structure on other Quaker meetinghouses in the United States. Built from materials collected and fabricated from the surrounding countryside, it could hold 2000 people and featured brick walls 24 inches thick, thickening to 28 inches at the base, with each column carved from a single log. Its interior was arranged for the business of the yearly meeting, with separate doors for men and women, two equally sized galleries, a long balcony for children, and an elevated three-tiered gallery at the front for elders. The Ohio Yearly Meetinghouse, home to the first yearly meeting west of the Allegheny Mountains, was used regularly until 1909, deeded to the state of Ohio in 1950, restored by the Ohio Historical Society, and opened to the public in 1963. Mount Pleasant also stood at the forefront of the abolitionist movement. In this part of the first free territory established in the United States, Blacks were paid to work throughout the area and possibly built many of the village's brick structures. At the 1815 Yearly Meeting, Quaker minister Charles Osborn, who had organized a Tennessee abolitionist society, spoke there, later moved his family to Mount Pleasant, and published The Philanthropist, the United States' first anti-slavery gazette. Quakers also protested slavery through the free market, and in 1848 the Ohio Yearly Meeting formed the Free Labor Store to sell only items produced without slave labor, though scarcity of such goods eventually forced it to close. Although slavery was illegal in Ohio, the Fugitive Slave Law of 1850 allowed slave owners to reclaim runaway slaves in free states, and many Ohioans helped escaped slaves continue north to Canada, while some came to Mount Pleasant itself to live and work. Among those who aided them was school teacher George Jenkins, in whose house fugitives sometimes hid through a hatch disguised as a dresser on the third floor.
