LOAD DATA INFILE failed "DATA TRUNCATED FOR COLUMN [0] AT ROW 1"

I'm trying to LOAD DATA INFILE because doing inserts is taking forever. But it fails, complaining that the data in the first column of the first row is being truncated. No error number.

The data is from geonames.org, one line per record, that I massaged to add dquotes around fields, tabs in between, and a newline to terminate lines.

The SQL command is
LOAD DATA INFILE "<fully-resolved filename>"
INTO TABLE <tablename>
FIELDS ENCLOSED BY '"' TERMINATED BY '\t'
LINES TERMINATED BY '\n '

The table def is
GeonameID INTEGER UNSIGNED NOT NULL DEFAULT 0,
Name VARCHAR(200) NOT NULL DEFAULT "",
ASCIIname VARCHAR(200) NOT NULL DEFAULT "",
AltNames VARCHAR(10000) NOT NULL DEFAULT "",
Lat DECIMAL(12,7) NOT NULL DEFAULT 0,
Lon DECIMAL(12,7) NOT NULL DEFAULT 0,
FeatureClass CHAR(1) NOT NULL DEFAULT "",
FeatureCode VARCHAR(10) NOT NULL DEFAULT "",
CountryCode CHAR(2) NOT NULL DEFAULT "",
AltCountryCodes CHAR(200) NOT NULL DEFAULT "",
ADM1 VARCHAR(20) NOT NULL DEFAULT "",
ADM2 VARCHAR(80) NOT NULL DEFAULT "",
ADM3 VARCHAR(20) NOT NULL DEFAULT "",
ADM4 VARCHAR(20) NOT NULL DEFAULT "",
Pop BIGINT NOT NULL DEFAULT 0,
ElevationM INTEGER NOT NULL DEFAULT 0,
DEM VARCHAR(80) NOT NULL DEFAULT "",
TimezoneIANA VARCHAR(40) NOT NULL DEFAULT "",
LastMod DATETIME NOT NULL DEFAULT "2019-01-07"