Answer:
Order is 6
Explanation:
The population of Portland Oregon has recently grown to more than 500,000.
The order of magnitude for the number of people in Portland means the power of 10. It means that we need to write 500,000 in form of 10 to the power. So,

It contains 6 zeroes. It means,

So, the order of magnitude for the number of people in Portland is 6.