The line graph depicts the average trip length with four types of means  used by American children in the range of 5 to 15 age from 1970 to 2020.
         
Overall
, the bus was the most popular vehicle among kids, Linking Words
whereas
 walking was the least selective choice. Of course, cycling decreased steadily and using cars had a fluctuating trend.
         To go into details, in 1970, children went by bus around 28 Linking Words
miles
 which was the peak point within the other three lines. Gradually, in each decade, it increased to reach  about 38 Use synonyms
miles
 in 2020. The least popular item was walking which started approximately with 16 Use synonyms
miles
 in 1970 and continued its significant reduction to around 5 Use synonyms
miles
 in 2000, Use synonyms
then
 it went up to under 10 Linking Words
miles
 in 2020.
          By looking at other parts of the graph, cycling had the same value as buses in 1970 and kept its trend to decline moderately to  reach  under 20 Use synonyms
miles
 in 2020. Car was another vehicle with just 20 Use synonyms
miles
 in 1970 and grew to more than 10 Use synonyms
miles
 in 2000 and Use synonyms
then
 dropped slightly to around 28 Linking Words
miles
 in 2020.Use synonyms