Altitude adjustments

The recipes in this book have been formulated for canning at sea level. High altitudes require a longer processing time, because the higher the elevation, the lower the temperature at which water boils. In general, you should add 1 minute to the processing time for every 1,000 feet (300 m) in altitude, or 2 minutes per 1,000 feet if the original processing time is more than 20 minutes. For altitudes higher than 5,000 feet (1,500 m), consider using a steam-pressure canner, which will allow for accurate processing time without overcooking the food.