Stock pens, of wood with concrete posts, originally covered over 100 acres of land around the Live Stock Exchange building. Probably built as early as 1902 when the Armour and Swift companies located their packing plants on the North Side, these pens were completely rebuilt after a 1911 fire. The pen area north of E. Exchange Avenue also includes a stucco yard office, several small wood-framed sheds, brick paved walkways, and a 1960 auction barn. Two long, parallel hay barns of brick stand on either side of an auxiliary rail track at the north end of the site. Now surmounted by a wooden overhead walkway built in 1970s for viewing cattle, many of these pens are still in use. This area is part of the Fort Worth Stockyards National Register Historic District.