Passenger traffic in and out of Charles M. Schulz-Sonoma County Airport set another monthly high in August, according to figures out Thursday.

In August, 45,551 airline passengers used the facility, 13.9 percent more than August 2017. Until last month, July represented record passenger count at the facility, airport officials said.

January through August, 290,680 airline passengers traveled through the Santa Rosa airport, up 9.2 percent over the same point last year.

Alaska, United and American airlines use the Wine Country airport regularly. Sun Country Airlines resumed seasonal service from Minneapolis–St. Paul to the airport June 29 and began service to Las Vegas on Aug. 30.

That destination was served briefly by Allegiant Air, which no longer flies out of Santa Rosa.

In August, officials at the county-run facility announced a deal with United Airlines which on March 8 will start using regional jets to fly a once-daily route to Denver — a key, direct link to a significant hub. At present, United makes a 17-minute hop from Santa Rosa to San Francisco, hoping to lure travelers to make connections to other flights.

Cost of the Denver run is being partly underwritten by the airport through waiving certain fees and with a commitment of money from tourism agencies tasked with marketing the area.

August’s individual airline counts show that Alaska reported 21.7 percent growth, serving 34,221 passengers. Load factor — a metric for how full the seats are — was 83 percent for the month, up 2.5 percent from August 2017. Year to date, Alaska reported 216,259 passengers, up 1.9 percent over last year through August.

American Airlines posted a 39.3 percent decline in passengers, serving 3,877 in August. Its load factor was 80 percent, up 8.1 percent. Year to date, the airline is running 10.5 percent ahead of last year, with 29,950 passengers.

United’s tally included a 10.2 percent jump over August 2017, serving 5,694 passengers with the load factor up 8.3 percent, to 65 percent. Passenger counts for the year are up 201 percent, at 40,671.

United Airlines began service between Santa Rosa (airport code STS) and San Francisco (SFO) on June 8, 2017. That service is expected to end when it begins Santa Rosa flights Denver.

Seasonal flier Sun Country reported 1,759 passengers in August, up 436.3 percent over August 2017. Its load factor was 75 percent, up 5.6 percent.