Can I scrape data from government websites if there is no mention about commercial usage?
Short answer: It all depends on how you plan to use the data you scraped. If you plan to upload it to your website, that is generally not OK since content can be copy write protected and you could get sued. If you plan to just use the data for personal use offline you should generally not have a problem.

I suggest you take a look at these links:


https://www.archives.gov/global-pages/privacy.html
http://www.ic.gc.ca/eic/site/icgc.nsf/eng/h_07033.html


Those are the privacy pages found at the bottom of the links you provided.

You will find all the information you need there, including email addresses to which you can write to if you have any questions. 

Though to help you out a bit, both of the sites you provided state that most of the content or all of it is copy write protected.

In conclusion, ask permission if you are going to re post the data somewhere on the internet. Websites that allow you to do so clearly state it in their privacy policies or terms of use.