The Downtown Concord Historic District encompasses most of the commercial heart of downtown Concord, New Hampshire, United States. Incorporated in 1734, Concord became the state capital in 1808 and the seat of Merrimack County in 1823. Economic growth followed, due in part to these government institutions and also to the rise of industry along the Merrimack River, which flows through the city east of the downtown area, and the arrival in the 1840s of the railroad. The New Hampshire State House was built in 1819 south of the traditional center of the city, and the commercial heart of the city began to take shape along the First New Hampshire Turnpike south of the State House. The district was listed on the National Register of Historic Places in 2000.