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_name_43 ( main_span_feet VARCHAR, main_span_metres VARCHAR, rank VARCHAR, year_opened VARCHAR, country VARCHAR )

### Question ###
What is the main span feet from opening year of 1936 in the United States with a rank greater than 47 and 421 main span metres?

### Accurate SQL ###

SELECT main_span_feet FROM table_name_43 WHERE year_opened = 1936 AND country = "united states" AND rank > 47 AND main_span_metres = "421"