Mallory, in my neighborhood, people don't use electric fences, they keep them in their backyards. However, these dogs are escape artists. I, too, walk my dog every morning and night, one hour each. I've had numerous encounters with stupid dogs who believe that the whole block is theirs.
As many have already suggested, carry pepper spray. I have used pepper spray on stray dogs before, and it really does give them something else to think about. I also carry a stun gun if pepper spray does not do the trick. In my experience, the dogs I have sprayed backed off, and totally forgot about my dog and I.
Connie also pointed out something important. Buy two cans, and carry your spray on a pouch, exposed and ready to be taken out at a moment's notice. ALWAYS carry your spray on the same spot, and think about where you're going to carry it. For example, if you're right handed, chances are that when you see a dog heading towards you, you're going to hold the leash with your right hand and deploy the spray with the left hand. Personally, I carry my spray on my left side, not far from my belt buckle. Practice taking your spray out of the pouch for at least about a minute or three, 2 or 3 times a week. Get yourself a good spray, and get one that is 10% concentrated, it will say so on the label. Good brands are Sabre, First Defense and Fox Labs, I use Sabre.
There are also different spray patterns, cone and stream. Stream is much more accurate, longer distance and less affected by wind conditions. This particular spray pattern is similar to that of a squirt gun. A cone spray pattern can be compared to a hair spray. I use the stream spray because it is much more accurate, shoots at longer distances and I don't have to worry too much about the wind shooting it back at me. Hold the can with your thumb on the spray lever/button, similar to the way you click a pen open.
When you encounter a strange dog, stand between your dog, and the stray dog, and yell at it. If it doesn't leave, spray it. I like to hold the very end of the leash, to the point where I can feel the hook of the leash. I do this because I can keep my dog close to me, as some dogs attempt to circle behind us.
I don't care if it's a little chihuahua, or a cute looking poodle, if it's off-leash and attempting to approach us, I'm going to spray it. If the owners call the police, tell the police that you were afraid for your safety because you felt that the dog was going to bite you (Not your dog).
Connie mentioned to choose a different location for walks, and this is good advice. Because of the problem with stray dogs in my neighborhood, I decided to walk my dog elsewhere. When there is no time to drive elsewhere, then I'll have no choice, but to walk in the neighborhood. It's not really such a big deal.