What can I use to kill weeds in sidewalk cracks?

One cup of salt to one gallon water. Saturate the weeds and they'll wither in a few days. The object is to get down to the roots. Warning: this will kill everything.

Boil the water, leaver out the salt

Make a mixture of white vinegar and water 50 50 add a dab of soap and salt.

Or, you can purchase ROUND UP - Do not use near grass, because it will also affect the

grass. Very effective on weeds, etc.

******Now, ROUND UP also has a new spray for weeds within the grass...********

You are are asking for a good weed killer for sidewalk and driveway cracks.... the Original weed killer. ROUND UP. You won't be disappointed.

Round up is very toxic to the environment