PORTLAND — Maine has made progress in adopting laws to stem human trafficking, but remains in the bottom half of all states in terms of the strength and breadth of those laws, according to rankings released Wednesday by the national Polaris Project.

Wednesday’s state-by-state ratings represented the Washington, D.C.-based anti-slavery organization’s fourth such annual report.

“We believe the prevalence of this issue is much larger than most people realize,” said Bradley Myles, CEO of the Polaris Project in a Wednesday morning conference call to announce the 2013 report. “I think the reason this is getting more attention now is that people are having their own encounters with the issue, people are seeing it in their communities and are wanting to get involved.”

In the 2013 ratings, the number of states in the Polaris Project’s top-ranked Tier 1 category for human trafficking laws grew from 21 to 32. Maine is one of 19 — including the nation’s capital — to have failed thus far to obtain the group’s highest rating.

Under new legislation, LD 1159, signed into law by Gov. Paul LePage last month, the definition of human trafficking in the state will be expanded to officially criminalize victimizing another individual for profit, and “promotion of prostitution” will be renamed “sex trafficking.”

But while the new law helped move Maine up in the organization’s four-tiered system from Tier 3 to Tier 2 in the latest version of the report, the Polaris Project still found deficiencies in the amount of training available to law enforcement on the issue of human trafficking, among other things.

Arguing that prostitutes are frequently victims of sex trafficking at the hands of abusive so-called pimps, the organization also docked the Pine Tree State for not having a law allowing prostitution convictions to be expunged from a victim’s criminal record. The Polaris Project additionally called on Maine to implement “Safe Haven” programs that make counseling and protective services immediately available for children discovered in the sex trade.

The subject of trafficking minors for sex attracted headlines last month when the FBI confirmed that three of the child prostitution victims discovered during a three-day, 150-arrest sting operation came from Maine.

Bill Legere, head of the Auburn-based nonprofit Foundation for Hope & Grace, said Maine youths are being coerced into prostitution through drug debts and blackmail — traffickers holding addictive drugs or embarrassing photos over the heads of their victims, for instance.

Legere also said his organization is hearing about an increase of cases in which landlords are pressuring low-income tenants to provide sex services in lieu of rent.

“When you start hearing their stories, you realize [many of the victims] ran away from their rural homes when they were 13 or 14, they came to Lewiston and started couch surfing with friends, then became tied into the sex trade by drug dealers,” he said. “People still don’t really believe this happens. They don’t believe these at-risk youths from rural communities could really be targets for organized crime up and down the East Coast.”

Legere said in many cases, prostitution becomes the latest step in a cycle that begins with domestic abuse and drug experimentation.

“We’re finding that these girls and boys are often first victims of child abuse, they’ve witnessed violence in the home … [and] they’ve been introduced to drugs at an age where they’re impressionable,” he said. “These are kids that are highly, highly vulnerable.”

Myles said an estimated 20 million people are sold as slaves of human traffickers, which market individuals for labor or sex, across the globe. He said “hundreds of thousands” of those are being trafficked within the United States.

“[Human trafficking is] alive and well and certainly is rampant. I view this more than just a human trafficking issue, I view it as a human rights issue,” said Cindy McCain — wife of U.S. Sen. John McCain, R-Ariz., and head of that state’s task force on the issue — during the Wednesday Polaris Project conference call.

The Polaris Project’s human trafficking hotline received 44 calls placed from Maine in 2012. That compares to 46 in 2011, and could represent a new approximate baseline for human trafficking tips in the state after two years in which the organization fielded less than half that many — 22 and 20 calls in 2009 and 2010, respectively.

While the Polaris Project hotline is just one way victims of human trafficking or those suspicious of the activity can seek help — the Maine Coalition Against Sexual Assault also has a support line at 800-871-7741, for instance — the national organization did report a difference in 2012 with regard to the places in Maine from which calls were originating.

In 2011, the vast majority of Maine calls to the nationwide hotline came from Portland. The state’s largest city accounted for 12 of the calls, with the next most coming from Bar Harbor, with four.

In 2012, the much smaller coastal community of Ellsworth shot up to tie Portland at the top of the list with eight calls each. Monmouth came in second in the most recent year for which data is available, with five. Compared with Portland’s approximate population of 66,000 people, Ellsworth has less than 7,800 residents and Monmouth has just more than 4,000.

Neither Ellsworth nor Monmouth had any calls placed to the national hotline in the previous year.

Legere said his organization has worked with anti-slavery advocates in India, where poor, rural communities on the outskirts of the country are seen by traffickers as prime locations to kidnap new victims. He said he believes that same model is being used by traffickers in the United States.

“There seems to be this appreciation that rural states are almost sources for this pipeline, places where they can be ahead of the curve,” he said. “If that’s what they’re doing in places like India, countries where human trafficking has been going on for centuries, is it safe to assume that traffickers here are similarly looking at rural states like Maine, New Hampshire and Vermont? I think it’s naive to assume that this is just a slumland problem.”