I was going to suggest this but I don't think it would prevent being pulled into secondary.
Also, make sure you tell them you are on TN status or they will happily wave you through on B1 which you won't know until you download your updated I94.
> Also, make sure you tell them you are on TN status or they will happily wave you through on B1 which you won't know until you download your updated I94.
Bingo. I had the unfortunate experience of crossing after obtaining a renewal through USCIS, but before my original TN had expired.
Despite giving them all of documentation, including the I-797A and new I94, the agent entered me based on my old TN, which expired.... a couple days later.
Also, make sure you tell them you are on TN status or they will happily wave you through on B1 which you won't know until you download your updated I94.