LITTLE ROCK, Ark. (AP) — A casino legalization proposal that two Native American tribes have each contributed more than $1 million to support was approved Wednesday to appear on the Arkansas ballot in November.

Secretary of State Mark Martin's office said supporters of the proposed constitutional amendment had submitted 99,988 valid signatures from registered voters, more than the nearly 85,000 needed to qualify for the ballot. The group behind the measure, Driving Arkansas Forward, turned in more than 138,000 signatures.

The proposal would allow casino gambling at Oaklawn, a Hot Springs horse...