I am always uneasy at the idea of carrying around a fixed blade. For this reason, my backpack knife is a multitool (A fantastic Leatherman Blast, which saved the day already many times). I would like to know where I can find information and procedures to safely carry around a knife (if at all) when it comes to fixed blade, but also more in general for any kind of knife.
Laws vary greatly by region, and are subject to being changed at any time. That being said, there are a few sites I used when looking up the knife laws in California.
http://en.wikipedia.org/wiki/Knife_legislation Provides a good overview of knife laws, but did not provide the specifics I need. It's worth browsing the sources that they reference however.
http://knife-expert.com/sta-law.htm Seems to have a good summary of knife laws for each state.
http://thefiringline.com/library/blades/knifelaws.html Very high level overview of state knife laws in a table, showing the concealed vs open carry status.
I wouldn't take any of these as fact, just as guidelines or resources to help you locate your official state / region's laws regarding knife laws.
I carry a fixed blade knife almost every day and it has a 4.5 inch blade (the Cold Steel Roachbelly, if you were wondering), and nobody has stopped me for it. I'm not sure what the legal length for a fixed blade is, though. I know that for a folding it's 3.5",but I don't know what it is for fixed.It might also be 3.5", but I don't know.