Which headquarter's truck has the highest shipments in year 2016?
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
CREATE TABLE city
(
    city_id    INTEGER
            primary key,
    city_name  TEXT,
    state      TEXT,
    population INTEGER,
    area       REAL
);
CREATE TABLE customer
(
    cust_id        INTEGER
            primary key,
    cust_name      TEXT,
    annual_revenue INTEGER,
    cust_type      TEXT,
    address        TEXT,
    city           TEXT,
    state          TEXT,
    zip            REAL,
    phone          TEXT
);
CREATE TABLE driver
(
    driver_id  INTEGER
            primary key,
    first_name TEXT,
    last_name  TEXT,
    address    TEXT,
    city       TEXT,
    state      TEXT,
    zip_code   INTEGER,
    phone      TEXT
);
CREATE TABLE truck
(
    truck_id   INTEGER
            primary key,
    make       TEXT,
    model_year INTEGER
);
CREATE TABLE shipment
(
    ship_id   INTEGER
            primary key,
    cust_id   INTEGER,
    weight    REAL,
    truck_id  INTEGER,
    driver_id INTEGER,
    city_id   INTEGER,
    ship_date TEXT,
    foreign key (cust_id) references customer(cust_id),
    foreign key (city_id) references city(city_id),
    foreign key (driver_id) references driver(driver_id),
    foreign key (truck_id) references truck(truck_id)
);
