Harriet Baskas

Special for USA TODAY

Denver-based Frontier Airlines today announced new non-stop service in 42 U.S. markets, with most flights beginning in mid-April.

Frontier is adding two new cities — Orlando and Philadelphia — from Austin, two cities — Orlando and Chicago (O’Hare) — from Charlotte, N.C., four new cities — Philadelphia, Houston (IAH), Los Angeles and San Francisco — from Cincinnati and four cities — Philadelphia, Los Angeles, San Francisco and Portland — from Cleveland.

Travelers will be able to fly Frontier to Atlanta and Cincinnati from Houston (IAH), to Chicago (O’Hare), Atlanta and Philadelphia from Kansas City, Mo., and to Atlanta, Philadelphia and Dallas/Fort Worth from Milwaukee.

Frontier will also begin flying to Chicago (O’Hare), Orlando and Philadelphia from Nashville, to Orlando and Philadelphia from New Orleans and to Atlanta, Detroit, Seattle and Portland from Phoenix.

Most flights start in mid-April, but at least a half dozen won’t roll out until May or June to accommodate delivery dates for some of the 18 new aircraft the carrier has on order.

None of these new flights will begin as daily service. Depending on the route, schedules are either Tuesday, Thursday and Sunday or Monday, Wednesday, Friday and Saturday.

“The day of week schedule helps capacity meet initial demand as we enter these new markets,” said Frontier spokesman Jim Faulkner.

The new routes are being introduced with fares as low as $39 one-way and target markets the Denver-based carrier considers “historically overpriced and underserved.” In in most cases the new routes put Frontier up against service offered by Delta, United, American or Southwest.

Details on the 42 new routes are below:

Market Start Date Frequency AUS – MCO 6/15/16 Mondays, Wednesdays, Fridays and Saturdays AUS – PHL 5/15/16 Tuesdays, Thursdays and Sundays. CLT – MCO 4/15/16 Monday, Wednesdays, Fridays and Saturdays. CLT – ORD 4/15/16 Monday, Wednesdays, Fridays and Saturdays CVG – PHL 5/13/16 Monday, Wednesdays, Fridays and Saturdays CVG –IAH 4/15/16 Monday, Wednesdays, Fridays and Saturdays CVG –LAX 4/15/16 Monday, Wednesdays, Fridays and Saturdays CVG –SFO 4/14/16 Tuesday, Thursdays and Sundays CLE – PHL 4/15/16 Monday, Wednesdays, Fridays and Saturdays CLE – LAX 4/14/16 Tuesdays, Thursdays and Sundays CLE – SFO 4/5/16 Monday, Wednesdays, Fridays and Saturdays CLE – PDX 4/14/16 Tuesdays, Thursdays and Sundays IAH – ATL 4/14/16 Tuesday, Thursdays and Sundays IAH – CVG 4/15/16 Monday, Wednesdays, Fridays and Saturdays MCI – ORD 4/14/16 Monday, Wednesdays, Fridays and Saturdays MCI – ATL 4/14/16 Monday, Wednesdays, Fridays and Saturdays MCI – PHL 6/2/16 Tuesdays, Thursdays and Sundays MKE – ATL 4/15/16 MKE – PHL 6/2/16 Tuesdays, Thursdays and Sundays MKE – DFW 4/14/16 Tuesdays, Thursdays and Sundays BNA – ORD 4/14/16 Tuesdays, Thursdays and Sundays BNA – MCO 4/14/16 Monday, Wednesdays, Fridays and Saturdays BNA – PHL 4/15/16 Monday, Wednesdays, Fridays and Saturdays MSY – MCO 4/15/16 Monday, Wednesdays, Fridays and Saturdays MSY – PHL 4/14/16 Tuesdays, Thursdays and Sundays PHX – ATL 4/15/16 Monday, Wednesdays, Fridays and Saturdays PHX – DTW 4/15/16 Monday, Wednesdays, Fridays and Saturdays PHX – SEA 6/29/16 Monday, Wednesdays, Fridays and Saturdays PHX – PDX 6/30/16 Tuesdays, Thursdays and Sundays

Harriet Baskas is a Seattle-based airports and aviation writer and USA TODAY Travel's "At the Airport" columnist. She occasionally contributes to Ben Mutzabaugh's Today in the Sky blog. Follow her at twitter.com/hbaskas.