line width dynamic
Line graph with Dynamic width for lines
A line graph that lets you show two measures at once. While the line may be increasing (Sales dollars) the number of units shipped is declining. Have the line width on the graph increase and decrease to show your secondary measure.
Here's another example: my Shipping spend is increasing, but so is the Sum of Weight shipped. As the line shows a positive slope, the width of the line would be impacted by Sum of Weight (expanding, contracting).
Jonathan Huber commented
I searched to see if this idea had already been proposed and was shocked to see how few votes it has given this is one of the major competitive advantages of Tableau. Being able to scale the size of a mark based on another metric/measure lets you do more with less space because it gives people the ability to absorb multiple concepts in a single chart. The concept is explained under "Change the size of marks" here (same applies to lines as it does to the circles in the example): <https://onlinehelp.tableau.com/current/pro/desktop/en-us/viewparts_marks_markproperties.htm#SizeProp>