Living for 7 years in the USA, just got a job in Canada, want to be able to travel to the USA again.

I've been living for 7 years in the USA, I came as a tourist, unfortunately I loved the city and stayed. I applied for a job in Canada and I got it, so I need to go back to Mexico to be able to have all the paper work done. I really love this country, so I wan to be able to come and visit again, and travel in the USA. If I work in Canada for some years I'll be able to have the residence there, that will help me to be able to come back to the USA to travel? And now with the immigration reform, I don't know if it's the best option to leave now. I don't want to lose the opportunity to work in Canada and I don't want to lose the chance to be able to travel to the USA either. I've been working and paying taxes here in the USA. Thank you