For American Airlines Inc. and regional partner American Eagle, the fifth try from Dallas Love Field may be the charm.

American and American Eagle have had miserably low numbers on their Love Field flights to Austin, San Antonio, Kansas City and St. Louis since relaunching service at the Dallas airport in March 2006.

But nonstop flights from Dallas to Chicago begun in July seem to be succeeding where the others have not.

According to numbers from Dallas Love Field and flightstats.com, American Eagle filled 62 percent to 63 percent of its seats on the Dallas-Chicago flights in July, up 20 to 25 percentage points from what it was doing on its flights to Kansas City and Austin.

American spokesman Tim Smith didn't confirm the numbers, but he said the new flights to Chicago are clearly attracting more passengers per flight than the previous destinations.

"There are two things at work there that we think drive that – very big markets in and of themselves on both ends, and the fact that unlike previous Love Field service, which was basically point to point, you have a large connecting hub at the Chicago O'Hare end," Mr. Smith said.

In addition, the Dallas-Chicago service may benefit from the fact that American Eagle's flights are nonstop compared to the connecting or one-stop service offered by competitor Southwest Airlines Co., Mr. Smith said.

Fort Worth-based American's flights are scheduled for two hours and 15 minutes compared to at least three hours for Southwest's Dallas-Chicago flights.

"For some people, business travelers in particular, time is money, and nonstop is faster than any connecting itinerary," he said.

Before adding Chicago, American and American Eagle had tried to offer Love Field service to four other cities since 2006 – St. Louis, San Antonio, Austin and Kansas City – but couldn't attract very high loads on its flights.

On July 2, American Eagle stopped its eight daily flights to Kansas City and eight daily flights to Austin and instead started six daily flights to Chicago's O'Hare International Airport.

In July, American Eagle boarded 5,728 passengers at Love Field, down sharply from the 8,768 that climbed onboard in June.

But the flight cutbacks mean that it operated about 9,150 seats in July, compared with 20,650 in June.

The July numbers indicate that American filled nearly 63 percent of its seats out of Love Field – less than its systemwide average of 73 percent, but still a distinct improvement from what it had been achieving prior to that at Love.

By comparison, American Eagle's load factors were below 43 percent on its Kansas City and Austin flights in June.

Load factors "certainly improved since we started flying nonstop to Chicago O'Hare," Mr. Smith said.

A quirk in the federal law known as the Wright amendment permits American Eagle's jets to fly nonstop to Chicago but not those of Dallas-based Southwest.

The law, first passed in 1979 and modified several times since, allows nonstop flights from Love Field only to cities in Texas and eight other states – which does not include Illinois.

Trips beyond the Wright amendment perimeter require a stop for the passenger. But the law applies only to airplanes with more than 56 seats, such as Southwest's 137-seat Boeing 737s.

The Embraer ERJ-145 jets flown by American Eagle have 50 seats and thus their range isn't limited by the Wright amendment.