How to join this 2 lines. Not fitted each other

[Safwan24514475y7x7]

Both have the same stroke size but not fitted each others

[Monika Gause · Accepted solution]

You might want to align them first.

Use the selection tool and turn on smart guides.

Grab one line by an anchor point and drag it on the anchor point of the other line you want to align it to. The smart guides will tell you when you hit.

Then select both lines and Object > Path > Join.