Reading Comprehension

Read the passage and answer the question.

Before refrigeration, many communities relied on ice harvested from frozen lakes and rivers during winter. Workers used saws to cut the ice into large blocks, which were then dragged to insulated buildings called icehouses. Packed in sawdust to slow melting, the blocks could last well into summer. Wealthy families bought the ice to preserve food and chill drinks, and a whole industry grew around shipping it to warmer regions. This trade declined only when mechanical refrigeration became affordable in the early twentieth century, making it possible to produce ice anywhere at any time of year.