WASHINGTON — Members of the huge millennial generation are less religious, less likely to call themselves "patriotic" and significantly more‎ liberal than older generations, new research shows.

Although adults aged 18-33 are more likely to call themselves political independents than their elders are, they are also more likely to vote Democratic. Their views favoring activist government, as well as their stands on social issues such as gay rights, reinforce that voting behavior, an extensive study by the Pew Research Center shows.

The youngest generation of adults, born after 1980, has the most optimism about the country. That comes despite the economic difficulties that a large share of them have experienced since entering the workforce. And it stands in contrast with some previous generations: Baby boomers, for example, born between 1946 and 1964, were less optimistic than their elders at this stage of their lives.

The millennials are also the only generation of adults with more people who identify themselves as liberals than as conservatives. Just less than one-third of millennials call themselves liberals while about one-quarter identify as conservative.

By contrast, among the baby boom generation, 41 percent call themselves conservative and 21 percent liberal. On this and most other issues, the views of Generation X (born 1965-1980) fall between those of the baby boom and millennial generations, and the views of those born before the baby boom are more conservative.

The liberal views of the youngest adult generation show up on a range of issues. Nearly seven in 10 say they support same-sex marriage and they are twice as likely to see gay and lesbian couples raising children as a good thing for the country than as a negative, which puts them at odds with older generations. They are also far more likely to favor legalization of marijuana. Opinions on abortion and gun control, by contrast, show little generational difference.

Just more than half of millennials say they favor a "bigger government providing more services." On the question of government, the much greater racial diversity of the millennial generation plays a key role. About four in 10 are non-white — a much larger percentage than in older age groups. Their generally liberal views shape the generation's outlook although whites in the millennial generation also hold more liberal views on government than white members of older generations.

Only about one in four millennials have wed, compared with more than one-third of Generation X when they were in their 20s and 30s, and nearly half the baby boomers. That decline in marriage rates may reflect the lessened attachment the generation has to other institutions, such as religion or nationalism. Almost three in 10 say they are religiously unaffiliated. Just less than half say that "patriotic" describes them well.

Members of the generation are the best educated in U.S. history, but also have the most student-loan debt. Their unemployment rate, 13 percent as of January, is significantly higher than that of older workers. Yet, millennials have a positive view about their economic futures, the survey showed. A majority believe that they eventually will have "enough to lead the kind of life I want."