Load US state bounding boxes from CSV - Source: https://anthonylouisdagostino.com/bounding-boxes-for-all-us-states/

fdw_us_state_bbox.sql

CREATE EXTENSION IF NOT EXISTS file_fdw;
CREATE EXTENSION IF NOT EXISTS postgis;

CREATE SERVER fdw_files FOREIGN DATA WRAPPER file_fdw;

CREATE FOREIGN TABLE public.fdw_us_state_bbox
(
    id INT,
    fips TEXT,
    state_code TEXT,
    state_name TEXT,
    x_min FLOAT,
    y_min FLOAT,
    x_max FLOAT,
    y_max FLOAT
)
SERVER fdw_files OPTIONS 
(
    program 'wget -q -O - "https://gist.githubusercontent.com/a8dx/2340f9527af64f8ef8439366de981168/raw/81d876daea10eab5c2675811c39bcd18a79a9212/US_State_Bounding_Boxes.csv"',
    format 'csv',
    header 'true'
);

CREATE MATERIALIZED VIEW public.us_state_bbox AS
SELECT id, fips, state_code, state_name,
       CASE WHEN state_code NOT IN ('AK', 'HI', 'AS', 'PR', 'MP', 'GU', 'VI') THEN True
            ELSE False
            END AS lower48,
        ST_Transform(
            ST_SetSRID(
                ST_MakeBox2D(
                    ST_Point(x_min, y_min),
                    ST_Point(x_max, y_max)),
                4326),
            3857)
            AS geom
    FROM public.fdw_us_state_bbox
;

Example usage, return only lower 48 states + D.C..

SELECT *
	FROM public.us_state_bbox 
	WHERE lower48
;