The box plot shows the distribution of bus riders. To find the least number of bus riders, we look at the leftmost part of the plot, which represents the minimum value.

From the plot, the least number of bus riders appears to be 70.

Would you like more details on interpreting box plots or any other related concepts? Here are some follow-up questions you may find interesting:

1. What does the box in the box plot represent?
2. How do you calculate the median from a box plot?
3. What is the difference between the minimum and maximum values in a box plot?
4. How can you use box plots to compare data sets?
5. What does the "whisker" in a box plot signify?

Tip: Box plots are great for visualizing the spread and central tendency of data, especially when comparing multiple sets.