In 2014, 34 percent of adults between the ages of 18 and 64 didn’t see or talk to a physician, according to a new report from the Centers for Disease Control and Prevention (CDC).

Study coauthors Lindsey I. Black, MPH, and Jeannine S. Schiller, MPH, also examined where Americans have the most difficulty in accessing care, and found wide disparities between different regions.

Western states and one in the South had the highest rates of adults who reported not seeing or speaking with a doctor in 2014: Montana was the highest at 48.1 percent, followed by South Dakota (47.7 percent), Nevada (43.7 percent), New Mexico (41.7 percent) and South Carolina (41.7 percent).

The lowest rate was found in Vermont (15.9 percent), followed by Delaware (18.3 percent), Virginia (23.9 percent), Pennsylvania (26.4 percent) and Michigan (27.2 percent).

Many of those same states remained on the high and low ends when measuring the number of respondents without a usual place of medical care. Nationally, 17.2 percent of adults said they either had no regular physician or clinic or considered the emergency room their go-to destination when they’re sick or need health advice. The state-by-state numbers ranged from 2.1 percent in Vermont to 26.7 percent in Nevada.

The authors also found mixed results when they tried to figure out whether these high or low percentages correlated to a state’s type of Affordable Care Act marketplace and Medicaid expansion.

On the question of whether respondents didn’t have a regular physician or clinic, there wasn’t much variation between state-run, federal-run and partnership marketplaces, while partnership marketplace states had a slightly lower percentage of adults who said they hadn’t seen a physician in the prior 12 months.

States that expanded Medicaid did have slightly lower average percentages of adults with no regular doctor (16.6 percent versus 18.2 percent for non-expansion states), but the difference wasn’t significant when it came to the doctor visit question (33.3 percent in expansion states said they hadn’t seen a physician in 2014 versus 34.8 percent in non-expansion states).