The United States' under-18 population has reached a historic high, according to a mid-1998 projection from the U.S. Census Bureau. While the surge in post-World War II births caused a temporary jump that peaked in 1966 and then declined, the current increase will only continue to climb, demographers report.

The implications range from a rush of new products aimed at children to increases in violent crime.

• The Census Bureau pegs today's under-18 population at 70.2 million -- surpassing the 1966 record of 69.9 million.

• School enrollments have set a record at 52 million children.

• By 2020, the number of children in the U.S. should hit 77.6 million.

• Experts say that while the mid-1960s records were occasioned by faster birth rates after the war, today's increases are immigrant-driven.

Immigrants are driving the numbers in two ways: new arrivals and the reality that immigrant families tend to have larger numbers of children than native-born families. The latest generation of Americans is 66 percent white and non-Hispanic -- compared to 74 percent in 1980.

Demographers report that the number of Hispanic children is increasing so fast that one in five children will be of Hispanic origin by 2020.

Nevertheless, the share of youths in the U.S. population has declined from 36 percent in 1966 to 26 percent today -- and will be only 24 percent by 2020.