回复：Living address question in 485

With what document you drive back and forth across the US/Canada border? It it is H1b visa/H1b I-94 or L1 or AP, I think there is no problem as long as you keep it valid until your 485 is approved or move back to US before its expiration.
Otherwise, you have abandoned your 485 once you leave US even if you have another type valid visa. However, if your 140 is approved, you can file for consular processing and get your US green card in Canada.