Band 7+: 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 graphs illustrate the changing pattern of population in thousands across three counties in the United States of Oregon between 1940 and 2000.

Overall, the population across three counties in Oregon state showed notable differences over the sixty-year period. In Washington, the number rose significantly from 75 thousands in 1940 to over 120 thousands in 1970, reaching a peak of over 240 thousands in 2000, the highest number reported at all times.

Population rates in Yamhill and Columbia started at similar levels around 30 thousands in 1940, increasing slightly to 35 thousands and 45 thousands in 1970, respectively. Over the next thirty years, the figures in both counties grew considerably, with population in Yamhill peaking at 90 thousands, slightly higher than population in Columbia, at over 75 thousands, the lowest number recorded in the same year.

In summary, there were significant changes in increasing populations across three counties throughout the period, with population in Washington increasing dramatically, culminating in 2000, while the population in Yamhill and Columbia showed steady upward patterns, registering moderate increases in the end.