The given line graph illustrates changes in the population of Columbia, Yamhill, and Washington between 1940 and 2000.
Overall, the populations of all three areas increased throughout the period. Washington had the largest population at every point in time and experienced the most significant growth, whereas Columbia remained the least populated area despite a steady rise.
Looking at the graph in more detail, Washington had the highest population, starting at approximately 75,000 in 1940. Its population increased gradually to around 100,000 by 1970 before rising sharply to just over 240,000 in 2000. As a result, Washington remained the most populous of the three regions throughout the period.
Meanwhile, Yamhill had a population of about 30,000 in 1940, which rose slightly to approximately 45,000 by 1970. After that, the figure continued to increase steadily, reaching around 90,000 in 2000. Similarly, Columbia followed a comparable trend. Its population stood at just under 30,000 at the beginning of the period and grew consistently to roughly 80,000 by the end. Although both regions experienced population growth, Columbia recorded the lowest population among the three areas in 2000.