Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_name_57 (maximum_diameter VARCHAR, name__year_commissioned_ VARCHAR)
### Question:
What is the maximum diameter of the Mid West Gas Pipeline (1999)?
### Answer:
SELECT maximum_diameter FROM table_name_57 WHERE name__year_commissioned_ = "mid west gas pipeline (1999)"