Please note that by answering this question I am not creating an attorney-client relationship with you and am answering it based upon the information as you presented in the question. My answer may be different if there is additional information you did not disclose. That said, generally traffic fines are civil in nature and should not affect a visa--Criminal convictions are the concern for approval of most visas. The outstanding traffic fines will most likely affect your credit and if you return to Vancouver, the court will have the option of seeking garnishment or other collection means to get the fines paid so my best recommendation would be to take care of the fines. By returning to Vancouver, WA, you will be subjecting yourself to the court's jurisdiction and should be prepared for possible consequences from that. I am assuming you will be on a student F-1 visa. While the fines themselves should not preclude you from obtaining the visa, you should check with your school to see if there is a negative affect from the unpaid fines--particularly regarding any student aid for which you may qualify.
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