Bill and Melinda Gates have donated $1 million to a Washington state campaign to expand background checks on gun sales. Initiative 594 has garnered significant attention and funds from tech giants. Microsoft co-founder Paul Allen donated $500,000 to it earlier this month. Also, venture capitalist Nick Hanauer has donated $1.4 million. Initiative 594 would require background checks for all gun sales in Washington state, including at gun shows. However, there would be some exemptions for antiques and family gifts. It has already earned $6 million in donations thus far.