The graph below shows the population change between 1940 and 2000 in three different counties in the U.S. state of Oregon.

The graph shows the

increase

in the

population

of three counties, Columbia, Yamhill and Washington in the U.S. state of Oregon, between 1940 and 2000. In 1940, Columbia had the lowest

population

of the three counties, at around 25,000.

This

is compared with about 30,000 in Yamhill and approximately 75,000 in Washington. By 1970, Columbia’s

population

had risen to just under 36,000.

Although

this

appears on the graph to be a gentle

increase

, it is in fact an

increase

of approximately 50%. Yamhill’s

population

also

rose by nearly 50% between 1940 and 1970: from 30,000 to just under 45,000.

However

, the greatest real

increase

was in Washington, where the

population

in 1970 had increased by approximately 75,000, to 125,000. The years 1970 to 2000 saw the populations of Columbia and Yamhill

increase

by approximately the same amounts that they had increased by the thirty years before. In 2000, Columbia’s

population

– at approximately 76,000 – was triple what it had been in 1940.

Likewise

, Yamhill’s

population

, at around 90,000, was almost triple what it was in 1940.

Although

Washington’s

increase

in

population

between 1940 and 1970 was large, its

increase

in the following thirty years was even sharper, rising from about 125,000 in 1970 to more than 240,000 in 2000.