How to connect a large amount of connected, exploded polylines

[rearlX89RH]

The file given to me is like it's almost a bunch of exploded polylines. None of these contour lines are joined all the way through. Points touch, so they are not separate. just joined. How do I connect them without individually selecting and joining? 

[Patchy]

PEDIT,  MULTIPLE, Join, use window and select them.

[j.palmeL29YX]

... or use the JOIN command: 

Command: join
Select source object or multiple objects to join at once: [select all lines, e.g. using a crossing window]

xxx found
Select objects to join: [ENTER]

xxx objects converted to nn polylines 

Command: 

[Kent1Cooper]

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@Patchy wrote:

PEDIT,  MULTIPLE, Join, use window and select them.

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[With the clarification that the Join option appears only after selecting them.  And you get asked for a fuzz distance, and further options continue the command, etc.]

[leeminardi]

If each set of contour lines have the correct elevation (z) value selecting the individual lines that form one contour line is much easier if you go to the front world view.  You can then select one elevation of lines with a narrow select window (pick left to right) or cross window (pick right to left) after giving a join command.