The issue is getting a visa that will permit you to work. Canada is still a separate country, and you need to obtain a visa to work in the US.
The LPN license is considered by immigration to be a technical job, not the same as the RN in their eyes.
As a Canadian passport holder, the nurse that has an RN can get a NAFTA TN Visa, which means just having a letter from an employer and a Visa Screen Certificate in hand. And presto, they are issued a visa at the border. But you need a Visa Screen Certificate to do this, and it is not issued to LPNs, only the RNs.
It is much easier to live in the US, then get a visa to work in the US.