This includes all 28 routes for all nine airlines that fly out of KPWM in Portland, Maine. I have individual liveries for American, Delta, Frontier, JetBlue, Southwest, Sun Country and United. Not sure if that of Cape Air and Elite Airways are in one of the megapacks. 
If you want to go for the extra realism, some routes are summer seasonal (including, strangely, Denver) and one only on Saturdays.

Each folder contains the following file formats: .FLT, .PLN, .FLT.SAVE, and .SPB. Use them as necessary.

To load your selected route, click "load/save" at the bottom of the World Map and navigate to the relevant folder.

(Please also check out my FedEx routes from the same airport.)

The airlines and routes:

American:

- Dallas, TX (Seasonal Service June 6 - Oct 3)

- Philadelphia

- Washington National

- New York City Laguardia

- Chicago O'Hare

- Charlotte

- Miami (Saturday only)

Cape Air:

- Boston

Delta:

- Atlanta

- Detroit

- New York City LaGuardia

Elite Airways:

- Orlando/Melbourne

- Sarasota/Bradenton

- Vero Beach

Frontier:

- Denver

- Fort Myers

- Orlando

- Raleigh/Durham

- Tampa

JetBlue:

- New York City JFK

Southwest:

- Nashville, TN (Summer Seasonal)

- Chicago Midway (Summer Seasonal)

- Baltimore/Washington

Sun Country:

- Minneapolis, MN (Summer Seasonal)

United:

- Chicago O'Hare

- Denver (Summer Seasonal)

- Newark/New York City

- Washington Dulles