Question: I'm moving to Canada from New York and I'm just checking in baggage along with plastic storage boxes. I'm trying to figure out the safest and most secure way to close the boxes. Any suggestions? Is this even possible? I'm flying Air Canada. I'd really appreciate feedback, packing is stressful enough.

Answer: 
You are flying FROM New York, hence you are at the mercy of TSA. And if the scanners show anything suspicious looking in your boxes, they will open them to inspect, in which case your duct tape, plastic wrap, etc will be cut open and useless.

What I usually do with boxes and cases like that is to get some compression straps for backpacking that are long enough to wrap around in either dimension and then strap the box shut (with straps going both directions and buckles on top of the lid). I then use duct tape to wrap around the case over the compression straps just below the lid. That way when TSA undoes the straps, they are right there ready to be refastened. I also tape a polite note, under where the buckles are, addressed to TSA, 'thanking them for their service protecting we travelers and asking them to be sure the straps are tightened down again' (not the exact wording ;-). It comes through just fine and I am often flying much further internationally.

This doesn't really address theft, but realistically when you consider how many bags get checked every day versus the number of actual thefts, air travel is relatively safe. And common sense says not to pack anything of value in a storage tote that is being checked.
Be aware that baggage handling systems are known not to be too gentle. It could pretty happily put your box upside down in a cart on a steep incline while heading to another part of the building at 30 km/h. When it gets there, it is usually tipped off the cart at speed and down a steep chute to the waiting luggage handlers below.

![siemens](https://www.siemens.com/press/pool/de/pressebilder/photonews/PN200806/PN200806-02_300dpi.jpg)

If my impression of your plastic box is correct (I'm thinking transparent IKEA ones), there are plenty of protruding edges and sharp corners it could get caught on. I'd advise using plenty of duct tape or IMHO taking cardboard boxes that are less likely to crack, better at absorbing impact and flush on the sides. I'd advise putting the heavy stuff at the bottom to encourage it to stay upright as desired if it is tall.