Although the basic principles of operation remain the same, locks along the Erie Canal have changed over the years. The canal's first locks, built with careful stonework by masons, measured 15 feet wide and 90 feet long. The concrete lock in use today, completed when the canal was modernized in the early 20th century, is nearly 45 feet wide and 300 feet long. Electric motors rather than human muscle now open and close huge metal gates weighing more than 20 tons. The area around the locks has also changed, as the homes of lock tenders and their families, sheds, barns, and popular canal stores have given way to power houses, lock operator control stands, and blue and yellow electrical cabinets.