While continuing my own research on tuberculosis over the years and in spite of some people encouraging me to neglect the problem because of their shoot the messenger attitude, I was surprised to find some articles and books published 70 to 100 years ago that claim that almost 100% of the population become infected with TB sometime in their lifetimes.
Some references can be found here:
http://sciliterature.50webs.com/TB2.htm
Also, a long time ago, I noticed that in TB reports, white people would usually be at the bottom of the list on race and ethnic groups (lower rates among whites). I found some articles that claim that tuberculosis began to increase in Europe starting in the 1400s, reached a peak in the 1700s and gradually declined after this. Tuberculosis was relatively rare outside of Europe prior to the 1800s. This resulted in European decendants developing a higher resistance to TB because of natural selection.
Its also known that genetics is a big factor in your resistance to TB. Before the bacteria was discovered that caused tuberculosis, some people thought it was inherited. Active tuberculosis tends to run in some families because of their lower resistance to TB. What's inherited is your ability to resist the disease from the TB.
I think this is useful information. If most of us had recent ancestors that were infected with TB (tubercle bacillus), and you don't have any family history of active tuberculosis then you probably inherited a high resistance to TB and there's a good chance you will never get any disease from it if you get infected with it as long as your immune system can keep it in check.
I also found some references that say that 10-15 million people in the US have latent tuberculosis right now. Some TB reports from the CDC say that up to 13 million people in the US have latent tuberculosis. This is about 4% of the population. I figured that if this group of people are spread throughout the US more or less evenly (more would be in more crowded areas), then most likely we all come into contact with people who have tuberculosis now and then, in spite of the wrong assumption that wherever you go there is no TB there. I use to assume this and I think most people assume this, too. Latent TB isn't contagious and even if you had brief contact with someone who had active TB in public, chances are you won't become infeccted with it. To become infected with TB, you need close contact with someone who has active TB for a long period of time, typically every day.