Band 9: The graph below shows the population change between 1940 and 2000 in three different counties in the U.S. state of Oregon. Summarise the information by selecting and reporting the main features, and make comparisons where relevant.

The line graph illustrates population changes in three Oregon counties, namely Columbia, Yamhill, and Washington, over a 60-year period, commencing from 1940.

Overall, it is evident that Washington County experienced the most dramatic population growth, particularly after 1980, while Colombia and Yamhill showed a steady yet much slower increase over the year.

In 1940, Columbia’s population stood at approximately 28,000, the smallest among the three counties. Yamhill followed closely with around 30,000 residents, while Washington had a significantly larger population of 75,000. By 1970, both Columbia and Yamhill had grown modestly, each reaching about 45,000 to 50,000 residents, marking an increase of roughly 50% in three decades. In contrast, Washington County’s population saw a sharper rise, almost doubling to reach around 125,000.

By 2000, Columbia and Yamhill saw further growth, with the former reaching 90,000 and the latter about 80,000. In contrast, Washington County’s population surged to approximately 250,000, more than doubling its 1970 figure, making it the largest county by far among the three.