According to UNICEF, 23.1% of American children under the age of 17 live in poverty. U.S. ranks 2nd in the economically developed countries. In the first place — Romania, where poverty is suffering from 25.5% of children.
The poverty rate of children (% of children living in families whose income is less than 50% of the median in their countries)
Translator's Note: The table is taken from the UNICEF report, which you can read here: http://www.unicef-irc.org/publications/pdf/rc10_eng.pdf
The data are based on the statistics of the European Union for the year 2009 in 29 countries (27 EU Member States plus Norway and Iceland). Most of them are also members of the Organization for Economic Cooperation and Development (OECD) countries except Bulgaria, Cyprus, Malta, Latvia, Lithuania and Romana, which includes the European Union, but not among the OECD countries — the first table in the study. Data on the relative child poverty are also given for another six OECD countries (Australia, Canada, Japan, New Zealand and the United States). Accordingly, the analysis of relative poverty includes 35 countries (Second table, which is here).