As baby boomers age, more local residents die. As economic hard times drag on, fewer children are born.
Those two facts have transformed multiple Sacramento neighborhoods in the last few years; in many, deaths now outnumber births.
Regionwide, about 1.8 births occurred per death in 2010, down 8 percent from 2005, according to new data from the state Department of Public Health. Deaths outpaced births in about one-third of the region's zip codes, with the trend most prevalent in El Dorado and Placer counties.
Schools close and populations shrink more often in areas where deaths outpace births, though some still grow due to migration.
This map shows the ratio of births to deaths during 2010 for the region's zip codes.
Source: California Department of Public Health, birth and death data.