Where to Watch Washington Nationals vs St. Louis Cardinals

You can watch on NATIONALS.TV, CARDINALS.TV and MLB.TV.

Yes. MLB.TV streams this game without a cable subscription, wherever you live.
NATIONALS.TV and CARDINALS.TV also stream it without cable, but these are regional products that work only inside their own market.

Both carry MLB.TV as a separate paid add-on, not part of their base plans. The trade is convenience: it runs inside one app with everything else you watch, billed through one account.

The game starts at 7:15 PM ET on 9/19.