The Lewis & Clark expedition planted the first wheat grown in Washington in 1805, near what is now Vancouver, located across the Columbia River from Portland.
Although some wheat farms were established in Eastern Washington in the 1860s, farming really took off in the 1880s, powered by mules and horses. As mechanization has replaced men, farms have gotten larger. Hundred acre fields that once took days to harvest with horses and manpower, are now routinely cut in a few hours using huge combines with 40 foot headers.
Such efficiency has reduced the number of farms. From 4,400 wheat farms in 1997, there were an estimated 2,500 farms in 2017. About 2.2 million acres of land is planted to wheat in Eastern Washington annually.