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_298550_1 ( area__km²_ INTEGER, capital VARCHAR )

### Question ###
What is the highest value of area when capital is San Juan?

### Accurate SQL ###

SELECT MAX(area__km²_) FROM table_298550_1 WHERE capital = "San Juan"