Can You Use a Stacked Bar Chart for Trend Over Time
Can You Use a Stacked Bar Chart for Trend Over Time

Can You Use a Stacked Bar Chart for Trend Over Time

The more important question is why are there 20 states that have not increased the minimum wage since 2011? But I cannot answer that!

In data visualization it is important to create effective charts. Not pretty charts, not charts with many colors, not fancy charts, not charts built in the latest tools. But effective. The right chart for the right data, colors with purpose, no clutter.

Sometimes however you have to think outside the box. And even if your chart is cluttered, or the use of color is not ideal, the data itself is so interesting, insightful, staggering, that your audience will spend the time to read it and analyze it regardless.

I find that comparison data between countries, states, cities tends to be exactly that – people expect to spend time to read it and understand it.

The Stacked Bar Chart

I recently built a bar chart for US state comparison. Which normally works. Bar charts are meant to be used for category comparison. However the data I had includes yearly trend since 2011 and shows how each state increased the minimum wage each year between 2011 and 2022.

Normally I would never turn to a stacked bar or column chart to show trend over time for multiple categories. I worked for a company in the past where the VP of Client Services insisted on using stacked bars for pretty much any data. I have seen over the years the confusion these charts can create.

However in this case I believe these stacked bars work.

Global data - Stacked Bar Chart for Trend Over Time - Minimum Wage by State - Stacked Bar Chart Example

Using stacked bars allows the audience to see not only the different minimum wage per state but also the amount the wage increased in a specific year. Stacked bar chart also shows if a state implemented a minimum wage increase each year since 2011 or only certain years for this time period.

The one thing I struggled with was choosing the colors. I still am not sure what the best color options would be.

This chart was built in Excel. I implemented styling on each stacked bar by using white outlines and a gradient color scheme.

I have two questions looking at this data:

  • Why are there 20 states that have not increased their minimum wage since 2011?
  • Why are there only two states, Colorado and Vermont, that implemented an increase to the minimum wage each year since 2011?