It depends on if your use of BLM means "lives of those of African-decent matter" or "the Black Lives Matter movement/group".

Personally i would expect the former to have more widespread support in America. The latter stands for many things that could be more controversial in the states. A DuckDuckGo for "blm demands"[0] returns the following NPR piece[1] from DC-based interviews. It lists BLM demands as:

  - Defund Police
  - No New Jails
  - Decriminalize Sex Work
  - Police-Free Schools
  - Drop Charges Against Protesters
  - End Cash Bail In Maryland
  - Ban Stop And Frisk

0: https://duckduckgo.com/?q=blm+demands

1: https://www.npr.org/local/305/2020/06/09/872859084/here-s-wh...

That any race matters more than any other race. If someone put "X Lives Matter" on a t-shirt, where X is any other race, they would be attacked, or at least fired from their job.

Similarly, you can go to work wearing a blue Biden hat, and nothing would happen. However, if you went to work wearing a red Trump hat, it might be your last day at work.

In a democratic society, this doesn't make sense.

THIS is why it’s so insidious. BLM is a well funded political organization with self-described marxist founders. It has about as much to do with black lives as the Nazi party had to do with “national socialism”.

Nobody thinks black lives don’t matter. This is very different from supporting BLM, however. Many prominent black public figures have come out denouncing BLM, and it isn’t because they think their own lives don’t matter.

The name is purely orwellian PR trickery that you can’t argue with, just like “antifa” is. It’s a remarkably effective tactic because most people assume it just means what the words say.