In article 6Duif.638864$tl2.159142@pd7tw3no, Don Kelly wrote:

The big American brands used to be made in a factory which simply stamped
and packaged a run of bulbs with a given brand name as ordered. Same bulb
different big name. The difference now is that the factory is in China.

Look at country of manufacture of "lamps"/"lightbulbs" of
higher-production-volume versions by the big name brands. These would
be 4-foot fluorescents as well as "A19" ("USA-regular lightbulb shape,
USA-regular lightbulb size") of wattages 25 to 100 watts.
Same for A19 incandescents of "store brand" that have same life
expectancy and light output specifications as any or more than one of the
"Big 3" brands.
Most of these sold in the USA were still made in the USA or in Canada
last time I looked at lightbulb packages when I was in stores that sold
lightbulbs (a week ago at most?). Mexico is a place that makes some
Philips lamps sold in the USA, although ones of lower production volume
than "A19" ones.

- Don Klipstein (Jr) )