Attending a conference in the US

If you are a Canadian citizen you do not need any kind of visa to enter the US for purposes that would normally be covered by a B1 visa. You simply show up at the US border (either the land border, the airport you land in, or the airport you leave from if it has pre-clearance) with your Canadian passport (or one of the other acceptable pieces of ID) and they will let you in.

You may or may not be asked questions about what you are doing in the US. It's probably wise to have a little bit of documentation to show what you are doing - like your ticket for the conference, copy of hotel bookings - but you probably won't need them. Make sure you have the address of the hotel and the conference.

As a Canadian citizen you will get a stamp in your passport with B1 in it when (if) you are admitted.

You will need to tell the immigration officials where you are staying (complete address in the US). Make sure you have that info handy.

Bring along some information indicating what the conference is (a flyer, for example), that you have registered for the conference, paid fees, if any, and so on and that indicates the nature of the conference. Show that if asked. In general, at any border, you should answer any questions completely truthfully but not volunteer information. Be prepared for more scrutiny if it's something that might be considered dubious such as Defcon. They may ask certain questions to assure themselves that you have strong ties to Canada and will definitely return to Canada on your booked flight. If there are circumstances such as a relative living in the US that could raise more questions.

Many trade shows and conferences, in my experience, don't admit under-18s so be prepared to answer that question. The main purpose of those rules is to stop visitors from bringing young children into situations where they might be disruptive or in danger (for example where there are live demonstrations of machinery on the show floor).