Blue laws are an artifact of an earlier era, state or local rules that prohibit stores from being open at certain times (usually Sunday, when most Christians have church services) or selling a certain product (usually alcohol). In Minnesota, for example, it is illegal to buy bottled alcohol on Sundays, though you can still order a drink at a restaurant.
North Dakota has blue laws too, but there's a movement to repeal them. That effort was narrowly stymied in the state legislature this week after debate which included lawmakers remarking the laws should stay to promote good wifely behavior. Sunday mornings should be used for "spending time with your wife, your husband. Making him breakfast, bringing it to him in bed and then after that go take your kids for a walk," said State Rep. Bernie Satrom. His comments were part of a broader list of ideas for things North Dakotans can do Sunday morning if they do not attend church but cannot legally work.
State Rep. Vernon Laning's concerns were more economic in nature. "I don't know about you," he said, "but my wife has no problem spending everything I earn in 6 and a half days. And I don't think it hurts at all to have a half day off." More seriously, Laning expressed concern for employees who are scheduled to work Sunday mornings and do not have an option to request that time off.