[IELTS Task 1] the number of population in three different countries - biggest in Washington

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 shows the number of population in three different countries in the United States of Oregon; Columbia, Yamhill and Washington during 6 decades, between 1940 and 2000, and it measures in thousands. It is clear that the population in three countries show a significant increase during the period.

The number of population in Columbia recorded the lowest in the state of Oregon, while the figure of Washington was the highest number of population 75,000 people in 1940. In terms of population, the number of population in Yamhill stood at the second position 30,000 people.

A more detailed look at the line graph shows that the number of Washington people inclined sharply from just over 120,000 people to above 240 thousand people between 1970 and 2000, a rise more than double the number of population. By contrast, the number of Columbian people experienced a steady incline, from approximately 25,000 people in 1940 to about 33 thousand people. Interestingly, the figure of population in Columbia and Yamhill had similar patterns which were a significant upward.

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My opinion
your introduction is not good. You repeat some words from title.
In specific, Title shows " The graph below shows the population", and your sentence starts with nearly the same " The line graph shows the number of population"

My suggestion: The line graph showsdepicts, reveals, compares, providesthe number of populationthe trend in the number of residents in three different countries in the United States o fOregonnamely Columbia, Yamhill and Washington during 6 decades, between 1940 and 2000, and it measures in thousands (you will give the unit of figure in body, so you do not need to write this sentence).

It is clear that the population in three countries show a significant increase during the period. (this sentence is too simple)
revise: It is clear that although each country saw a different change in data, all of three countries show ( you like this verb so much :)) experienced a significant increase during the period. Furthermore, The ranking in number of population for three countries remained stable throughout the years

The introduction is too bulky.
Why don't you start writing this: The line graph shows a large portion of the population living in Columbia, Yamhill and Washington,...


Columbia had a population of (write the figure number here, a number in the thousands). This was the lowest growth in fixed period.


similar significant upward patterns.


A period of rapid population growth in Washington