What is the longest an NFL team has gone without a WR TD catch?

Question

The Kansas City Chiefs have not had a wide receiver catch a touchdown pass so far this season (through Week 15). According to team stats, only running backs, fullbacks, and tight ends have caught a TD pass so far this season.

According to the NFL_Stats twitter account, the Chiefs haven't had a WR catch a TD pass since December 8, 2013:

The #Chiefs have not had a WR catch a TD pass since December 8th, 2013

That is 17 straight regular season games without a WR catching a TD pass (the Chiefs did have a WR catch a TD pass in their playoff game last season). A December 19 article on Steelers.com confirms this:

A Chiefs wide receiver hasn’t caught a touchdown pass in 17 straight games, since Dwayne Bowe on Dec. 8, 2013 at Washington.

Has an NFL team ever gone an entire season without a wide receiver catching a touchdown pass?

What is the longest streak of games an NFL team has gone without a wide receiver catching a touchdown pass?

Answer 1

"Has an NFL team ever gone an entire season without a wide receiver catching a touchdown pass?"

Yes, according to the Sporting News, three teams from before the NFL's modern era did that:

only three teams have gone through a season without a wide receiver catching a touchdown, and all of them played in a bygone era. The last team to do it was the Giants in 1964, when the Bears had the NFL's best passing offense at just over 200 yards per game.

Another article mentions the two teams besides the 1964 Giants who did that:

Delving further into history yields other teams, including 1960 Washington and 1950 Pittsburgh, who didn't have a "wide receiver" catch a TD pass.

That article also says that before 2014, no team had ever had fewer than 2 touchdown catches by a wide receiver in a 16 game season:

The fewest touchdown catches by a group of wide receivers in a 16-game season is two, set by the 1981 Saints and matched by the 2004 Giants.

But then in 2014, the Kansas City Chiefs went the entire season without a wide receiver catching a touchdown pass (from the Sporting News article):

Alex Smith hit wide receiver Dwayne Bowe for a 22-yard touchdown in the first quarter of a 45-10 win over the Redskins on Dec. 8, 2013. 385 days and 19 games later, we're still waiting to put "Chiefs wide receiver" and "touchdown" in the same sentence. [...] The Chiefs, eliminated from playoff contention after a Ravens win, officially finished an entire season without a WR catching a touchdown pass.

The Chiefs finally ended the streak at 21 regular season games when WR Jeremy Maclin caught a TD pass in Week 3 of the 2015 season.