Try looking on line for convertible car seats.

there are several brands of car seat that "convert" into a stroller.

the kid may want to walk, but 3/4 of the strollers I see in the park are
just used to carry the cargo that goes with the kid anyway.

J. Hansen wrote:

I am planning a trip including my five year old son to Niagara falls
next weekend. We are flying into Niagra Falls International Airport
(IAG) and plan to stay only for the day. The problem is how to get
from the airport to the falls and back. The natural choice is a taxi,
but what do we do with the car seat once we get there? I'd rather not
carry it around all day. We could of course rent a car, but that
seems like an overkill just to create a place to put the car seat. Is
there any place to store a car seat near the falls? Is there any other
reasonable transportation from IAG to the falls for five adults and
two children that will not require a car seat (we can always leave it
on the plane)? or am I overly cautious in thinking we need a car seat
for two ten minute taxi rides?

Jeff H, CP-AM&SEL, CFII