title: Pandas Merge Result Output Next Row
body: <p>Suppose I have two dataframes</p>
  <pre><code>df_1
  
  city           state           salary
  New York        NY             85000
  Chicago         IL             65000
  Miami           FL             75000
  Dallas          TX             78000
  Seattle         WA             96000
  
  df_2
  
  city           state           taxes
  New York        NY             15000
  Chicago         IL             5000
  Miami           FL             6500
  </code></pre>
  <p>Next, I join the two dataframes</p>
  <pre><code>joined_df = df_1.merge(df_2, how='inner', left_on=['city'], right_on = ['city'])
  </code></pre>
  <p>The Result:</p>
  <pre><code>joined_df
  
  city           state           salary           city           state        taxes
  New York        NY             85000           New York          NY         15000
  Chicago         IL             65000           Chicago           IL         5000
  Miami           FL             75000           Miami             FL         6500
  </code></pre>
  <p>Is there anyway I can stack the two dataframes on top of each other joining on the city instead of extending the line horizontally, like below:</p>
  <p>Requested:</p>
  <pre><code>joined_df
  
  city             state         salary          taxes
  New York          NY            85000
  New York          NY                           15000
  Chicago           IL            65000
  Chicago           IL                           5000
  Miami             FL            75000
  Miami             FL                           6500
  </code></pre>
  <p>How can I do this in Pandas!</p>