This post is part of a series examining challenges involved in the 2020 Census and what’s at stake for California. Click here to see our full coverage.

As the country gears up for the 2020 Census, one big challenge will be ensuring a complete and accurate count of young children. Nationwide, the 2010 Census missed nearly a million children under five years old, including about 210,000 young Californians, according to Census Bureau estimates.

This undercount—which has worsened in the past few decades—has consequences for political representation at the federal, state, and local levels. An inaccurate census could also affect federal funding for educational and health programs. For example, the distribution of Head Start funds depends in part on census counts to determine the number of young children living in poverty.

Young children were undercounted by 4.6% in 2010, the worst undercount across all age groups. In contrast, people in their late teens and early twenties, as well as those over age 50, were overcounted—meaning people in these age groups were often erroneously included in multiple households.

figure - Young Children Were the Age Group Least Likely To Be Counted Accurately in the 2010 Census

The count of young children in California was even less accurate: 7.7% of Californians ages 0–4 were undercounted in the 2010 Census, the third-highest rate in the nation. In follow-up research, the Census Bureau has found that households in Monterey County, much of the Central Valley, Los Angeles County, the Inland Empire, and Imperial County were especially likely to indicate confusion over whether to include young children when completing their census questionnaires.

Multiple reasons account for why young children are often missed in the census. Families may forget to include newborns or children who split their time between two homes. Young children in low-income families and those with young or single parents are especially at risk of being undercounted.

Young children are also more likely than other age groups to live in households with multiple generations, unmarried partners, nonrelatives, or extended family—which can lead to confusion over who should be included in the census form. African American, Latino, and Native American children are much more likely than white children to live in households with these kinds of “complex” living arrangements, which have probably become more common in California because of the housing crisis.

figure - Young Children Are Much More Likely To Be in Families with “Complex” Living Arrangements

In preparation for the 2020 Census, the Census Bureau has taken several steps to improve its count of young children. These include adjusting the wording on the census form to clarify that everyone living in the household should be included, as well as undertaking advertising and education campaigns about the importance of counting all children.

California has committed $100 million for census outreach, and the governor has proposed an additional $54 million for the next fiscal year. The California Complete Count Committee, which is spearheading the state’s efforts, has allocated these funds to the state’s hard-to-count communities, with options for many other organizations to receive funding. Given what we know about the historical difficulties of counting young children, it will be particularly important for community organizations and agencies working with young children and families to be involved with outreach efforts.