In the U.S., increase in the birth rate between 1946 and 1964; also, the generation born in the U.S. during that period. The hardships and uncertainties of the Great Depression and World War II led many unmarried couples to delay marriage and many married couples to delay having children. The war's end, followed by a sustained period of economic prosperity (the 1950s and early 1960s), was accompanied by a surge in population. The sheer size of the baby-boom generation (some 75 million) magnified its impact on society: the growth of families led to a migration from cities to suburbs in the postwar years, prompting a building boom in housing, schools, and shopping malls. As the boomers reached young adulthood in the 1960s and '70s, their tastes in music and their hair and dress styles strongly influenced the national culture, and the political activism of some contributed to the unpopularity of the Vietnam War. As they aged and prospered in the 1980s and '90s, their buying habits determined the course of many consumer industries, including automobiles. The needs of baby boomers during their retirement years were expected to strain public resources.