Polltakers for the General Social Survey, done by NORC at the University of Chicago have asked a representative national sample this question since 1977: “When a person has a disease that cannot be cured, do you think doctors should be allowed by law to end the patient’s life by some painless means if the patient and his family request it?”

The proportion of Americans responding affirmatively, always a substantial majority, has bounced between 66 and 69 percent for 15 years. But support was not evenly distributed: Such laws initially were enacted in states with predominantly white populations like Oregon, and to date the vast majority of patients who have used them are white.

“I hear people talk all the time about this being a rich white person’s issue,” said Donna Smith, legislative manager for the District of Columbia at the group Compassion and Choices, who is African-American. “Now, we have proof on the ground that that is not true.”

Indeed, aid in dying has expanded to more diverse locales. Non-Hispanic whites represent a minority of Californians. Colorado is more than 21 percent Latino. In the District of Columbia, nearly half of whose residents are African-American, five of six black council members voted in favor of the legislation.

State medical societies, once active foes of aid-in-dying initiatives, also have begun shifting their positions, citing deep divisions among their members. The California Medical Association, the Colorado Medical Society and the Medical Society of the District of Columbia all took officially neutral stances as legislators and voters debated, depriving opponents of influential allies. So has the state medical society in Maryland, where legislators plan to reintroduce a bill (the third attempt) this month.

The American Medical Association, an opponent since 1993, has asked its Council on Ethical and Judicial Affairs to look at the aid-in-dying issue and submit a report in June, though without recommending any policy.

But even as the idea gains acceptance, passage of a bill or ballot measure does not always make aid in dying broadly available to those who want it. In addition to the safeguards the law requires, its practice can be balky — at least in the early stages.