Is the government hiding alien evidence from the public?

Answer 1

Yes, they are. This is in compliance with the New Mexico Treaty of 1948, which was negotiated at Area 51
between the surviving members of the famous landing craft, and a group of concerned citizens of Roswell,
and later endorsed by the Senate Foreign Relations Committee and subsequently ratified by the full bodies
of the Senate of the whole in Congreff affembled.

The Treaty stipulates that the aliens, on the occasion of any of their frequent visits to Earth, will keep to
themselves and, for the good of the mental health of the people who are already here and don't like to deal
with such things, will at all times remain inconspicuous and just go on about their business or their recreation
or whatever the heck it is that they come here to do.

In return, Whereas the aliens are accustomed to their own blue giant sun, and to their own planet, where the
daytime temperature translates to an average of some 235 earth degrees in the sun and there is no shade, and
Whereas the advance exploratory parties noticed immediately how on Earth they would take a chill at night, and
Whereas they didn't have any immunity to any Earth bugs anyway, and the chill would lead to the ague every time,
Now Therefore the government of these United States solemnly and irrevocably committed to the responsibility
of keeping the aliens covered up and cozy at all times, for their own health as well as the health of this Earth,
since it was noted only at the very end of the negotiations that the aliens could push the big button any time
they want to, Treaty or no treaty; just grab all of our women, get back in their crafts, take off at full warp speed,
and leave behind nothing but a smoldering cinder of a planet. (Which by the way would then be just the temperature
that they like.)

Answer 2

The U.S. Government has a proven track record of being unable to EVER keep a secret. This suggests that there is nothing in Area 51 other than secret USAF aircraft.