jox, I agree with the response above by MSPNWA.
Once you arrive at DCA
on Air Canada Jazz at Terminal A, you will have to go through Security again at the entrance to the USAirways concourse in Terminal C.
However, keep the following in mind:
Flights to the U.S. from Ottawa pre-clear customs in Ottawa (to the best of my knowledge) so the flight will arrive DCA
as a domestic flight.
As mentioned earlier, the airport is not terribly large. The last time I was there, I did not record the amount of time it took to walk from Terminal A to Terminal C but I don't think it would be much more than 20 minutes, so I think a connection time of 58 minutes will probably be sufficient provided your Air Canada Jazz flight is on time.
I hope you enjoy your trip. Terminal A, where you will arrive on Air Canada Jazz, was built around 1970 and was originally called the Northwest/TWA terminal. Some folks affectionately called it the "banjo" concourse because of its shape.
As you walk from Terminal A to Terminal C, you will pass through the lobby of what was the original terminal of Washington National Airport. If you have time, there is a nice photo display on the wall depicting the history of National airport. On the opposite side of the photo wall is the outside observation deck (now closed) but it still provides a nice view of the runway (01/19) and the Potomac River and if you use your imagination you can still see United DC6s DC7s, Capital Viscounts, and Eastern Convairs and Constellations. There is also a small museum on the mezzanine above and in front of the photo wall (on the north end of the lobby). Once you get beyond the original, main lobby, you enter the new terminal. It is shown as Terminals B and C on diagrams, but in reality, it is one terminal with three concourses.
Overall, if your Air Canada Jazz flight arrives on time, a 58 minute connection from Terminal A to Terminal C should be sufficient.
And one last thing, the airport is officially known as Ronald Reagan Washington National Airport, but some of us aviation "purists" cringe when we hear that. To me, it will always be known simply as "Washington National Airport," and I cannot bring myself to call it anything else.