This dataset uses U.S. Census table B17020 - Poverty Status by Age
The data shows the number of people per locality, the overall number of people living below the poverty level per locality, and then the number of people under age 18 living below the poverty level per locality. This last data element is broken down into three segments - aged <6 years, 6-11 years, and 12-17 years, which when added together equal the total number of children under age 18 living below the poverty level per locality.

This dataset provides annual numbers for each state in the United States for 2013-2018. Includes the following data: total population, median income, and number of people living at or below the poverty level.

Helpful information on using U.S. Census data is found at https://censusreporter.org/

This link provides data and visualizations based of the American Community Survey for Poverty Status In The Past 12 Months By Age per County

"ATSDR’s Geospatial Research, Analysis & Services Program (GRASP) created Centers for Disease Control and Prevention Social Vulnerability Index (CDC SVI or simply SVI, hereafter) to help public health officials and emergency response planners identify and map the communities that will most likely need support before, during, and after a hazardous event.

SVI indicates the relative vulnerability of every U.S. Census tract. Census tracts are subdivisions of counties for which the Census collects statistical data. SVI ranks the tracts on 15 social factors, including unemployment, minority status, and disability, and further groups them into four related themes. Thus, each tract receives a ranking for each Census variable and for each of the four themes, as well as an overall ranking."

For more see https://www.atsdr.cdc.gov/placeandhealth/svi/documentation/SVI_documentation_2018.html