Legend based on 2 columns

[#1]

Dear all,

I have a huge data table like following

Continent        State          City                  Population

USA              Pennsylvania          Philadelphia           ----

 USA              Pennsylvania        Harrisburg                ----

USA              California                San Diego

USA              California                San Fransisco

 Europe       France                      Paris

  Europe       France                                                             another_city_in_France

I am creating a scatter plot of the population.  In order to put a legend, I want to use a unique marker for each state.

Then for each state , I want to color that marker differently corresponding to each city.

I know if I do row legend, I can color by a particular  column. But if I need to color and mark in above mentioned way, I want to know the most efficient way to do it.

Right now I create a summary of state and then assign markers.

Then I select all rows corresponding to a particular state and assign colors to that set manually, which is very inefficient for the long data table.

Thanks

[#2]

Here is an example using Graph Builder.  Population is on the Y axis, I couldn't tell what you were using for your X axis so I just chose Ozone level.  I Overlayed by State and Colored by City.