Most immediately, it would allow Maryland Live!, the state's new mega-casino south of Baltimore, as well as two smaller ones, to stay open 24 hours a day and to begin offering dice and card games, such as craps, blackjack and roulette, by early next year. The full magnitude of the measure would be felt in 2016, when a proposed $800 million casino could be completed at National Harbor in Prince George's County. Maryland voters have faced an unprecedented blizzard of competing and often confusing political ads, including disagreements about how much money would go to education. In all, groups for and against the measure spent more than $90 million - by far Maryland's most expensive campaign ever. Political proponents of the measure point to estimates from state analysts that say it could bring in $150 million annually for education by 2016, although similar estimates have proved overly optimistic from the state's current casinos. The advocates also claim it could create some 12,000 new direct and indirect jobs. Polls in recent weeks made clear that the ad deluge had been effective at eroding support for gambling as a source of education funding and that the measure would be decided by a much more narrow margin than four years ago, when Maryland voters overwhelmingly endorsed building five slots-only casinos. Then, casino owners mostly banded together, viewing Maryland's nascent market as lucrative for all. But in the years since, the casino market in the mid-Atlantic has stratified. To protect their competing interests, gaming companies spent like never before in a Maryland election. MGM Resorts, the company angling to build at National Harbor, poured nearly $41 million into a campaign backing the measure. Penn National Gaming, which operates Hollywood Casino and Resort in Charles Town, W.Va., spent even more, seeking to protect its revenue from gamblers in Maryland who now travel to West Virginia. With millions more from the Peterson Cos., the developer of National Harbor, and Caesars Entertainment, which wants table games at a Harrah's-brand casino slated for Baltimore, the total spent for and against the measure topped $90 million, according to campaign reports filed Monday. For comparison, that amount - spent in less than three months - is more than Democrats and Republicans spent combined over the past 10 years to wage three hotly contested governors races. Calculated another way, the cost of the casino battle eclipsed Maryland's entire universe of political spending.