We can read and save JSON data in single query

Declare @JSON varchar(max)

SELECT @JSON=BulkColumn
FROM OPENROWSET (BULK 'D:\zipcodesgeodata\geonames.JSON', SINGLE_CLOB) import

INSERT INTO zipcodes (country_code, postal_code, place_name, latitude, longitude)

SELECT *
FROM OPENJSON (@JSON)
WITH 
(   
    country_code    varchar(50),
    postal_code    varchar(50),
    place_name    varchar(500),
    latitude    varchar(50),
    longitude    varchar(50)
)