period of rapid economic growth; high-growth era
Often refers specifically to Japan's post-WWII economic boom (roughly mid-1950s to early 1970s).
Japan's period of rapid economic growth lasted from the mid-1950s to the early 1970s.
高度成長期には、多くの地方から都市へ人口が移動した。
During the high-growth era, many people moved from rural areas to cities.