The point at which a child becomes an adolescent is defined by the onset of puberty or by the beginning of the teenage stage. Adolescence is also viewed as ending with the teenage stage. However, in some individuals (particularly females), puberty begins in the preadolescence years.
Population of Grundy County. Last official estimated population of Grundy County was 50,098 (year 2014)[1]. This was 0.016% of total US population and 0.4% of total Illinois state population. Area of Grundy County is 430.4 miÂ² (=1114.9 kmÂ²), in this year population density was 116.39 p/miÂ². If population growth rate would be same as in period 2010-2014 (+0.02%/yr), Grundy County population in 2017 would be 50,124 .
St. Clair County is the oldest county in the U.S. state of Illinois. According to the 2010 census, it had a population of 270,056, making it the eighth most populous county in Illinois and the most populous in the southern portion of the state. Its county seat is Belleville. The county was founded in 1790, before the establishment of Illinois itself, and contains the historic French settlement and former mission, Cahokia Village, founded 1697.