Table 1.

Grouping of Treatment and Control States for Medicaid Expansion

Excluded States
Alaska1 Indiana1 Louisiana1 Montana1 Pennsylvania1		Arizona2,4 North Dakota3,4
Control States
Alabama Delaware5 Florida Georgia Idaho Kansas Maine Massachusetts5 Mississippi Missouri Nebraska New York5		North Carolina Oklahoma South Carolina South Dakota Tennessee Texas Utah Vermont5 Virginia Washington, DC5 Wisconsin Wyoming
Treatment States
Extensive Dental Coverage	Limited Dental Coverage	Emergency Dental Coverage
California Connecticut Iowa New Jersey New Mexico Ohio Oregon Rhode Island Washington	Arkansas Colorado Illinois Kentucky Michigan Minnesota	Hawaii Maryland Nevada New Hampshire West Virginia

Notes:

¹indicates states that were excluded in the main estimation of the difference-in-differences model identifying the Medicaid expansion effects because these states expanded in later 2015 and 2016.

²Arizona was excluded in the main estimation because it is a Medicaid expanding states but offers no dental coverage.

³North Dakota expanded Medicaid in 2014 and provides extensive dental benefits for traditional Medicaid adults, but provides no benefits for adults gaining coverage under the recent expansions.

⁴In sensitivity analysis, Arizona and North Dakota are added as control states.

⁵Delaware, Massachusetts, New York, Vermont, and Washington DC announced adopting the ACA Medicaid expansion in 2014, but these states had prior full or near full Medicaid expansions similar to ACA for both parents and childless adults. Thus, in our main analysis, we included these five states as control states. However, in sensitivity analysis, we switch both Massachusetts and New York as treatment states with extensive dental benefits, and DC and Vermont as treatment states with limited dental benefits. We keep Delaware as a control state because it offers no dental benefits.