JACKSONVILLE, FLA. ? At a recent Double-A baseball game, some fans in the second row joked about the home-plate umpire. The ump had an unusually thin waist and dirty-blonde hair that jutted out from behind a mask.

Must be a lady umpire, one of the fans said, never thinking he actually could be correct.

Two innings later, the fan assessed the umpire’s performance. “He might be young, but he looks like he’s consistent,” the spectator said. “So far, he’s called a good game.”

But the “he” behind the plate was in fact a woman named Ria Cortesio, and she’s accustomed to people saying she works in a man’s profession.

“In this country, if you’re a woman, you can be a Supreme Court justice,” Cortesio said. “You can be a senator. You can be a governor. But you can’t be a major-league umpire.

“For some reason, it’s so unheard of in this culture, and I think that’s really sad.”

One day, Cortesio, 30, may become the first female to umpire a regular-season Major League Baseball game. But she didn’t set out to break barriers. Call her a “pioneer” and she winces because four other women – Bernice Gera, Christine Wren, Pam Postema and Theresa Cox – umpired in the minors before her.

Still, out of the 225 people who will umpire minor-league baseball games this season, she will be the only female.

Yet she’s unique for other reasons. She graduated summa cum laude from Rice University, but her love for umpiring and baseball led her to a profession that now pays her, at most, $2,700 a month during the season.

She also has a wry sense of humor. A few years ago, a reporter from Tennessee reminded her that a fan once left Postema a frying pan and a nasty note at home plate.

“Actually,” Cortesio responded, “I could use a frying pan.”

Players and managers say she does a good job – and that she likes to have fun during games.

“She sings all the songs that are being played in-between innings,” said Jacksonville Suns catcher A.J. Ellis. “She’ll sing in your ear all game.”

The other day, she cracked a joke when the stadium loudspeaker announced the name of West Tennessee Diamond Jaxx third baseman Ronald Prettyman. Ellis recalled that she said, “So this guy thinks he’s a pretty man?”

Sometimes the players joke with her, too. When she throws a baseball to the pitcher, some say, “You throw like a girl.”

She grew up in Rock Island, Ill., a city on the shores of the Mississippi River. She and her cousins would play baseball at their grandfather’s home in eastern Iowa, pretending they played for the St. Louis Cardinals.

Cortesio became interested in umpiring in 1993, the summer when the Mississippi flooded. The high waters forced the Class A Quad City River Bandits to move from their stadium in Davenport, Iowa, to local high-school fields.

Between games of a doubleheader at North Scott High in Eldridge, Iowa, she went to the parking lot to get something out of her car; the umpires happened to be in the parking lot, too.

At that moment, umpiring started to fascinate her.

“I can still see them there,” she said. “It struck me at that moment because they were not the stereotype that I had of umpires, which was the big, fat, grouchy old men.”

When she finished at Rice, she went to her own version of graduate school: five weeks at the Jim Evans Academy of Professional Baseball Umpiring in Kissimmee, Fla.

“I think her work on the field speaks for itself,” said Evans, who umpired in the majors from 1972 to 1999. “I don’t think sex should be a criterion for umpiring in the big leagues.”

Only the best students from Evans’ academy and the Harry Wendelstedt School for Umpires in Daytona Beach qualify to attend a 10-day evaluation course in Cocoa Beach, run by the Professional Baseball Umpire Corporation.

PBUC employs all of the umpires from Rookie ball to Triple-A, and ranks the ones up to Double-A based on their performance. The top-ranked umpires are first in line for a promotion.

Cortesio is ranked first in Double-A, and she’d be the first one to be called up to Triple-A if there’s an opening.

“What has happened with Ria is that we have projected that there’s a good possibility that she’ll advance,” said Mike Fitzpatrick, PBUC’s executive director. “But we didn’t have as many openings as we anticipated.”

For Cortesio, however, time’s running out.

After nine years in minor-league baseball, five of them in the Double-A Southern League, money is a concern.

“I’m kind of antsy to get out of Double-A,” she said.