### Database Schema:
CREATE TABLE driver (
	driver_id	INTEGER	NULL	PRIMARY KEY,
	first_name	TEXT	NULL,
	last_name	TEXT	NULL,
	address	TEXT	NULL,
	city	TEXT	NULL,
	state	TEXT	NULL,
	zip_code	INTEGER	NULL,
	phone	TEXT	NULL
);

CREATE TABLE city (
	city_id	INTEGER	NULL	PRIMARY KEY,
	city_name	TEXT	NULL,
	state	TEXT	NULL,
	population	INTEGER	NULL,
	area	REAL	NULL
);

CREATE TABLE shipment (
	ship_id	INTEGER	NULL	PRIMARY KEY,
	cust_id	INTEGER	NULL,
	weight	REAL	NULL,
	truck_id	INTEGER	NULL,
	driver_id	INTEGER	NULL,
	city_id	INTEGER	NULL,
	ship_date	TEXT	NULL,
	foreign key (truck_id) references truck (truck_id),
	foreign key (driver_id) references driver (driver_id),
	foreign key (city_id) references city (city_id),
	foreign key (cust_id) references customer (cust_id)
);

CREATE TABLE truck (
	truck_id	INTEGER	NULL	PRIMARY KEY,
	make	TEXT	NULL,
	model_year	INTEGER	NULL
);

CREATE TABLE customer (
	cust_id	INTEGER	NULL	PRIMARY KEY,
	cust_name	TEXT	NULL,
	annual_revenue	INTEGER	NULL,
	cust_type	TEXT	NULL,
	address	TEXT	NULL,
	city	TEXT	NULL,
	state	TEXT	NULL,
	zip	REAL	NULL,
	phone	TEXT	NULL
);

### User's Query:
Which headquarter's truck has the highest shipments in year 2016?

### Extra Knowledge:
in 2016 refers to CAST(ship_date AS DATE) = 2016; make = 'Peterbilt' means headquarter is 'Texas (TX)', make = 'Mack' means headquarter is 'North Carolina (NC)', make = 'Kenworth' means headquarter is 'Washington (WA)'; highest shipment refers to MAX(COUNT(ship_id))
SELECT CASE WHEN T2.make = 'Peterbilt' THEN 'Texas (TX)' WHEN T2.make = 'Mack' THEN 'North Carolina (NC)' WHEN T2.make = 'Kenworth' THEN 'Washington (WA)' END AS "result" FROM shipment AS T1 INNER JOIN truck AS T2 ON T1.truck_id = T2.truck_id WHERE CAST(T1.ship_date AS DATE) = 2016 GROUP BY T2.make ORDER BY COUNT(T1.ship_id) DESC LIMIT 1