At last count there are 2,300,534 of these in the USA. You have probably seen 150 today without knowing it. What is it?

The correct answer is city blocks.

The last time city blocks were counted, there were 2,300,534 in the United States. The riddle is assuming that you have passed by around 150 city blocks in one day. This is about 7.5 miles. Depending on the activities you were involved in or whether or not you live in a city, would affect if this is true. However, it is not the important part of the riddle.

I'm pretty sure the answer is city blocks