Colorado has become the 19th US state to vote in legalized sports betting this week, albeit by a surprisingly narrow margin of 51% to 49% according to unofficial returns. More than 1.3 million Colorado citizens voted on Proposition DD, a bipartisan ballot measure put together by policy makers that will bring legal sports wagering to the Centennial State by next May.

Essentially, Colorado’s 33 casinos will be able to offer in-person and online wagering on professional, collegiate, motor and Olympic sports. Proposition DD, co-sponsored by Democratic House Majority Leader Alec Garnett and Republican House Minority Leader Patrick Neville, seeks a 10% flat tax on net sports betting proceeds, with a view to raising circa $11m in the next financial year commencing July 1. 

According to coverage by the Associated Press, Garnett and Neville cited several reasons for the close vote, including voters’ rejection on Tuesday of another tax measure that would have allowed the state to keep revenue it currently is obligated to refund to taxpayers.

The betting ballot language didn’t help, Garnett said in the AP, referring to a segment that read: “Shall state taxes be increased by twenty-nine million dollars annually to fund state water projects and commitments and to pay for the regulation of sports betting. …”

That language was inspired by the Taxpayer’s Bill of Rights (TABOR), a constitutional amendment that requires voter approval of any new taxes, tax increases, revenue retention measures and bonding.

“We campaigned hard to explain to people that this is a new tax, but on something that right now is totally illegal,” said Neville, a proponent of TABOR. “This was as close as it was because a lot of voters got the two mixed up.”