U.S. Population

Re “World Population Reaches 6 Billion,” July 17: Zero Population Growth national spokesman Peter Kostmayer claims that population growth “momentum”--the tendency of population to increase for 70 years after reaching replacement-level fertility--is the reason U.S. population is projected to exceed one-half billion by 2060.

While Kostmayer’s explanation is politically correct, it is wrong. U.S. fertility has been at or below replacement level for nearly 30 years. If momentum were the primary factor, U.S. population would stabilize in the next few decades. But U.S. Census projections indicate continued growth through 2050, with a greater increase in 2050 than in 1999.

If immigration had been halted in 1970, U.S. population would be stable at about 230 million in 2050--40 million below our current population. Thus the sole reason U.S. population is projected to double by 2060 is immigration. In California immigration accounts for at least 75% of population growth.

KIM BERRY

Citrus Heights