HARRISBURG - The numbers aren't looking good for Pennsylvania.

The latest U.S. Census Bureau estimates show the state on track to lose at least one, and possibly two Congressional seats come 2020. That is when official population numbers are released and the state begins the once-a-decade politically charged process of re-drawing Congressional and state legislative maps.

A report in late December by Election Data Services, a Virginia-based political consulting firm, named Pennsylvania as one of nine states that stand to lose at least one U.S. House seat, continuing a shift in political clout in Washington from the Northeast and Midwest to fast-growing areas in the West and South.

The other potential losers include Michigan, New York, Ohio, Rhode Island and Illinois. On the flip side, Texas could gain up to four seats, Florida up to two and Arizona, Colorado and Oregon one each. New Jersey, according to the report, would not lose or gain any seats.

Though a one-seat loss over a decade may not be cause for alarm, the downward spiral in Pennsylvania's delegation strength over the last century should be, political analysts say.

In 1910, the state had 36 U.S. House members. Today, it has 18. By 2021, that number could drop to 16 - a decrease that would also cut Pennsylvania's electoral votes and political influence in presidential elections.

"A one-seat change is not gigantic in terms of clout in Washington - but if you compare it to a few generations ago, it is a significant change," said Chris Borick, a political science professor and director of the Muhlenberg College Institute of Public Opinion.

Though it remains the sixth most populous state, Pennsylvania dropped an estimated 7,677 residents from 2015 to 2016 - its first population loss in 31 years, according to an Inquirer analysis of census data.

Kimball Brace, president of Election Data Services, said jobs and the economy play a significant role in migration patterns, but the steady population shift over the last six decades began, as research has shown, because of something more mundane: the widespread use of air conditioning.

"People wanted to get out of the upper Midwest and the snow belt and move to a warmer climate," he said. "With air conditioning, they could do that more comfortably."

Before 2016, Pennsylvania was growing, but at a sluggish pace. Since 2010, the state grew by 0.6 percent - the eighth-slowest pace of any state, census figures show.

And the commonwealth's population only grew in that span because of immigration and because births outpaced deaths. (The latter also happened in every state except for West Virginia.)

Brace said it is possible the next three years could bring a change in momentum for Pennsylvania or other states, but suggested it might take a major event. Louisiana, for instance, had been set to gain a congressional seat between 2000 and 2010, but Hurricane Katrina and its aftermath wiped out that possibility.

The state ended up losing a seat in Congress after the 2010 census.

The population updates every 10 years also drive reapportionment of Congressional seats and redrawing of state legislative maps.

Congressional reapportionment in Pennsylvania is controlled by the party in power in the state Capitol. It has been heavily criticized over the years for creating shamelessly gerrymandered districts - areas with seemingly illogical geographic boundaries that are drawn based on political registration figures to protect incumbents and further party interests.

Though the governor's office is now held by a Democrat, Tom Wolf, Republicans hold historic majorities in both legislative chambers. If that holds, they will drive the legislation determining the new district maps - and deciding which districts must consolidate.

"We're watching it," said longtime U.S. Rep. Bob Brady, a Democrat from Philadelphia who said he does not believe the three Congressional districts Democrats hold in and around the city, for both demographic and political reasons, will be touched in any reapportionment.

But, he added: "That's why it's so important to keep Gov. Wolf in the governor's office. He's the veto guy if they try to get too crazy."

As it stands, 13 of the state's 18 U.S. House seats are held by Republicans.

(Pennsylvania's two senators are split - a Democrat, and a Republican - but their seats are not impacted by census changes).

Good government groups and reform-minded legislators argue that such lopsided representation is no accident.

During the last reapportionment in 2011, when the state again lost one congressional seat, Republicans controlled both the legislature and the governor's office.

The congressional maps they produced came under heavy fire for creating districts that protected GOP incumbents and positioned the party for further dominance. The Republican-held 7th Congressional district outside of Philadelphia, for instance, was redrawn in such a contorted way it prompted a Democratic legislator to launch a contest to determine what creature from Greek mythology it resembled.

The district now includes chunks of Montgomery, Chester and Delaware counties.

Longtime political analyst and pollster G. Terry Madonna at the time called the maps "the worst gerrymander in modern Pennsylvania history."

Carol Kuniholm chairs Fair Districts PA, a coalition of good government and other nonprofit groups with the singular purpose of changing - and de-politicizing - how the state decides Congressional and state legislative districts to create fairer elections.

In an interview, Kuniholm called the current mapping process "detrimental to democracy" because it creates extreme partisan districts that elect representatives less willing to compromise to achieve policy goals.

Kuniholm's group would like to see a nonpartisan citizens commission decide district boundaries - a change that would require legislative approval and approval by voters.

Such a sea change appears unlikely, if for no other reason that many legislative leaders don't see a problem with the current process.

"You already have a citizens commission," said Steve Miskin, spokesman for the House Republicans. "It's called the General Assembly of Pennsylvania, elected by the people."