ALBANY, N.Y. — Melissa Grothues and John Steele bailed from Buffalo last year.

Dissatisfied with their bank jobs, the 25-year-old college graduates sold the house in suburban Amherst, posted ads for possessions on Craigslist and drove cross country to San Diego for a fresh start.

“We were ready for a bigger city and to move on. There just weren’t many opportunities in Buffalo, job-wise,” Grothues said. “It just seemed like day-to-day there, every single person that I worked with would be miserable.”

The young couple is hardly alone in exiting upstate New York. More people are leaving the region than moving into it, contributing to a largely stagnant population. The trend has helped lead to New York losing four congressional seats in the last two Census counts and is about to cost the state some prestige. At some point early this year, Florida is expected to surpass New York as the third most populous state, according to projections by The Associated Press.

New York is home to about 19.65 million people, but the state’s slow growth is largely fueled by New York City, which has long attracted a large share of international immigrants and young adults, including many from upstate.

The story is different north of the Westchester-Rockland county line. The population of the 53 counties of upstate New York was essentially flat, decreasing by 0.1 percent from 2011 to 2012, according to the latest county-level Census estimates available.

Though there have been pockets of growth in the Hudson Valley and some other areas, many upstate areas grapple with a slow but steady loss of people.

Why are people leaving upstate New York?

Some complain that taxes in New York are too high. Others, like Grotheus, say there are better job opportunities elsewhere. State and local officials have had mixed success in luring high-tech companies and other new businesses to make up for jobs lost when large employers like Eastman Kodak Co. and Carrier Corp. scaled back or shifted operations elsewhere.

“Part of it is probably due to job loss in the major metropolitan areas like Buffalo, Rochester, Syracuse and Binghamton. They all had large employers that had to lay off a lot of people,” said Jan Vink of Cornell University’s Program on Applied Demographics.

Others blame the weather in upstate New York, where winters can be a trying mix of heavy snow and little sun.