I love to explore dive bars in every city I visit because it's an opportunity to meet locals and learn about other must see spots.  This is a cash only bar and there is no sign that informs you of this. It is just assumed because of its location and the dive reputation. I went during the day so got seats right on the bar.  There were only a few people.  I don't know how crowded it gets during evening hours.  Very friendly bartender and customers.  I would definitely go again.