I need to develop a thesis statement about factors that make it difficult for the government of the United States to protect its citizens. Some of the reasons I have in mind are poor national security and the sizes of its borders.
The first thing I would say about this is that you cannot use “poor national security” as a reason why the United States cannot protect its citizens (assuming that you are right to say that the US cannot do so). Poor national security and being unable to protect citizens are, in essence, the same thing so using that is like saying that the US can’t protect its citizens because it’s poor at protecting them.
That said, let us look at what we can use to explain our country’s alleged inability to protect its citizens. Other than the size of the country’s borders, I would talk about our country’s strong tradition of individual rights and our desire to protect our trade and other relationships with the rest of the world.
First, you might talk about trade and foreign relations as reasons why we cannot or will not close our borders more effectively. We could do more to prevent people from coming to this country illegally, but those things would also make it harder for people to enter the country as tourists or on business. We do not want to do these things (making it harder to get visas, making it harder to get through security at airports, etc) because they would reduce our ability to trade and they would make other countries (including our allies) unhappy.
Second, and perhaps most importantly, you have to think about our tradition of rights in this country. One right that many Americans cherish is the right to bear arms. This makes it much easier for our country to be flooded in firearms, which in turn makes it harder for the government to protect us. In addition, Americans are strongly opposed to anything that resembles a police state. We do not want to give the authorities greater power to keep us under surveillance. Because we want to maintain our privacy, it is very hard for the government to try to find out who might be planning to commit crimes or acts of terrorism and to prevent them from doing those things.
I would use these factors, plus the sheer size of our borders, as my reasons for why it is hard for the US to protect its citizens.