NEW YORK ( MainStreet) — What factors determine what kind of tip a server receives? Is it the service - or is it determined by gender, geography, race, religion, ethnic group or nationality? Are tips for wait service contingent upon the race of the customer?

According to mobile payment and merchant services aggregator Square Inc., San Francisco, tippers vary in generosity by location. Square provides an app for mobile payments. It is the little credit card reader you see attached to an smartphone or tablet when you pay your bill at a restaurant. This app has a tip feature.

The company has collected data from a wide variety of businesses who have their tipping feature enabled. Millions of sellers are able to accept credit cards via Square. The data collected represents tens of millions of transactions. They are currently processing tens of billions of dollars in payments annually.

According to Square data, the tipping patterns in the U.S. are as follows:

When customers left a tip, Alaska (17%), Arkansas (16.9%), and North Carolina (16.8%) had the three highest average tips for any U.S. state. By contrast, Delaware (14%), Hawaii (15.1%), and South Dakota (15.3%) were the three states with the lowest average tips.

Chicago has the highest proportion of residents who leave tips -- 63%. Some 62% of people in Denver leave tips, and residents in the Colorado city leave the largest tips for a single metro area - about 16.8% on average. Tippers are generous in Austin, too, with 62% leaving tips at an average of 16.2%.

Only 51% of customers in Atlanta and Tampa leave tips.

Those in Square's home office city of San Francisco are the cheapest tippers. They only leave 15.5%.

In short, employees who depend on tips would benefit by working in either Chicago, Denver or Austin.

Here is Square's infographic:

A 2007 Gallup poll determined 71% of people thought an appropriate tip was between 15 and 20%.

Gallup also reported the more money one makes, the more generous he is with the tip. Some 49% of those who made $75,000 or more a year tipped 20% or more compared to 35% of those who made between $30,000 and $74,000 per year and 25% of those who made less than $30,000 per year.

Of course, it could be stated, quite accurately, that those tipping 20% while making less than $30,000 per year are the most generous tippers since they have less resources, while eight% of those making over $75,000 per year who tip less than 15% are the stingiest.

Professor Michael Lynn of the Cornell University School of Hotel Administration, a recognized tipping expert, has done several comprehensive studies about tipping over a more than 30-year period of studying the practice.