Nevada urges the Department of Justice to act on illegal offshore gambling.
The fine is the second-largest handed down by the Nevada Gaming Commission, which has authority over disciplinary action.
The Democratic legislators say sports betting, now legal in 38 states plus the District of Columbia, has increased gambling addiction.
Pennsylvania is joining the short list of states where online casino-style gambling is available. Nevada, New Jersey and Delaware are the only other states where online casino gambling is legal.
The attorneys general of Pennsylvania and New Jersey have registered their objection to a Department of Justice legal opinion that could affect online gambling.
A legal opinion from the U.S. Department of Justice could threaten the viability of U.S. online gambling that crosses state lines.
Pennsylvania's governor has approved legislation authorizing a major expansion of gambling in what's already the nation's second-largest commercial casino state after Nevada.
After eight years of failed attempts to pass online gambling, lawmakers are advancing the first proposal that would legalize online poker in California.
Morgan Stanley has cut its estimate of the potential U.S. internet gambling market by nearly half. The firm now estimates the nationwide online betting market at $2.7 billion by 2020, down from an initial estimate of $5 billion.
A Utah congressman is reviving an effort to ban online gambling throughout the United States. The measure would reverse the Justice Department's 2011 decision allowing online gambling with the exception of sports betting.