In comparing private industry workers to state and local government workers, however, private industry worker participation lagged by a substantial margin.

While 81 percent of state and local government workers participated in plans — and participation rates varied depending on the type of plan offered — just 49 percent of workers in private industry participated. Those percentages do not include federal government workers, the military, agricultural workers, private household workers and the self-employed.

Workers are counted as having access to or participating in retirement benefits if they have access to or participate in at least one type of plan, whether it’s defined benefit or defined contribution; some workers, it said, may have access to or participate in both.

And the type of plan affected the participation rate, since “[p]articipation in defined benefit plans is often mandatory, subject to any applicable eligibility requirements, while participation in defined contribution plans is often voluntary.”

The study cautioned that, in comparing private and public sector data, differences in sectors must be taken into account, such as manufacturing and sales, which do not make up a substantial portion of state and local government activities, or administrative support positions, which constitute two thirds of state and local government workers, compared with just half of private industry.

Participation rates were lower in certain geographic areas, with the northeast and Midwest having the highest and the south and west having the lowest; in addition, smaller companies had both lower access and lower participation rates.