The bill has support from Attorney General Bob Ferguson.
The march, which is timed to the anniversary of Roe v Wade, took place as legislators considered bills that would broaden access to abortion services.
Democratic lawmakers are hopeful that this is the year for the Reproductive Parity Act.
Under the proposed law, it would take those who volunteer 14 days to retain their right to a firearm.
Having passed the House last year, the bill now appears to be stuck in a Senate committee.
One bill would discourage conversation therapy, while the other would encourage equitable treatment for elderly members of the LGTBQ community.
Five firearm bills go before state lawmakers.
The bill would aim to restore salmon while cutting down on toxins and noise pollution.
