The line graph compares the population growth in three counties of Oregon—Columbia, Yamhill, and Washington—over a 60-year period from 1940 to 2000.
Overall, while all three counties experienced population growth, Washington saw a dramatic surge after 1970, making it by far the most populous county by the end of the period. In contrast, Columbia and Yamhill grew at a much more modest and steady pace.
In 1940, Washington’s population stood at about 75,000, more than double that of Yamhill (around 30,000) and five times higher than Columbia (15,000). Over the next three decades, Washington’s figure rose gradually to approximately 120,000, before accelerating sharply to reach nearly 250,000 in 2000.
Yamhill, meanwhile, saw its population climb moderately from 30,000 to about 45,000 by 1970. Growth became more pronounced in the following years, and the county reached roughly 75,000 inhabitants in 2000.
Columbia consistently recorded the lowest numbers throughout the period. Its population increased slowly but steadily from 15,000 in 1940 to around 32,000 in 1970, and then grew further to approximately 60,000 by the end of the timeline, still lagging slightly behind Yamhill.