Besides the library, five inhabited structures are divided by the border. Most residents use the US entrances to avoid problems with the border patrol; crossing the border within buildings does not require official permission. A tool-and-die factory, once operated by the Butterfield division of Litton Industries, is also divided. The factory in Canada closed in 1982 after a lengthy strike by Canadian workers. The factory in Derby Line is open. It was bought in 1988 by Group Tivoly, a cutting tools company based in France, and has 160 employees.