Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_16463 ( "No. in season" real, "No. in series" real, "Title" text, "Directed by" text, "Written by" text, "Original air date" text, "U.S. viewers (million)" text )

### Question ###
How many millions of U.S. viewers watched the episode that first aired on March 31, 2013?

### Accurate SQL ###

SELECT "U.S. viewers (million)" FROM table_16463 WHERE "Original air date" = 'March 31, 2013'