In 1999, Frontier signed agreements to begin purchasing and leasing Airbus A318 and A319 jet aircraft and had also added Boeing 737-300 jetliners to its fleet as well. Also by September 1999, the airline was serving destinations from coast to coast in the U.S., having expanded its route network to include Atlanta (ATL); Baltimore (BWI); Bloomington/Normal, Illinois (BMI); Boston (BOS); Chicago (MDW, Midway Airport); Dallas/Fort Worth (DFW); Phoenix (PHX); Los Angeles (LAX); Minneapolis/St. Paul (MSP); New York City (LGA, LaGuardia Airport); Orlando (MCO); Portland, Oregon (PDX); Salt Lake City (SLC); San Diego (SAN); San Francisco (SFO); and Seattle (SEA), all served from its Denver hub.