I have been running a game of D&D for about a year and a half now. All of my players have an active interest in the campaign, show up regularly and very much enjoy our game; unfortunately, the we do have the tendency to go off into miscellaneous tangents that waste time. We all have such a good time my first instinct is to disregard this problem, but when I brought this issue up with the party at our last session the overwhelming consensus of the party was that they would also like to get rid of these sidebars. I find myself in a bit of a conundrum as I do not desire to destroy the pleasant atmosphere we have created by being super strict though I do feel that a more focused party would lead to a more enjoyable game. If anyone has found themselves in a similar situation I would very much like to hear your advice. Thank You!

The suggestion that come to mind is this:

Create some NPCs "ex-machina" that can point the party in the direction you want. These NPCs can be messengers, members of the factions or minions of the main villains that somehow respresent a menace for the party.

I wish I knew the answer to this. I have this exact same problem. Group pfaffs around a lot and then starts getting bored and checking phones. I try to drive them forward but it's like they actively resist doing things. Took two hours last session for them to just go to the damn adventure location that they knew was the adventure location because of things like whittling and asking random people in the street about the adventure location, as if they would know.

I think next time I'll have the adventure location blow up because they took too long to get there.

Rather than forcing direction, why not give a better incentive to follow it? Sometimes a lack of urgency can make people meander, or the prospect that they might be 'missing' out on things that are 'side' content. Make sure there is a clear reward for going the way you want, breadcrumb them along the right roads. Make sure the characters have a good reason to be going there, individually! Appeal to them as characters, appeal to their backstories! 

Trying to fully remove those tangents from the gaming experience is very likely to spoil the mood, since the going on of tangents being acceptable is one of the differences between fun and work.

Reducing them, however, can improve the feeling of getting stuff done during the session. So what I do with my group is embrace the tangents and distractions, get a good laugh in, but remember to polite direct the group back to the game itself (and since everyone wants to be playing the game, there is no struggle to get them back to it) - and then after another bit of play, embrace the next distraction.

Tangents are part of the game for us. When my group would get together, we'd probably get a 80/20 split with 80% game time and 20% tangents. Our DM would somehow take notes of what the tangents were and spin them into side missions or extend the campaign goals. Sometimes a good tangent can be very useful and creative.

If needed, toss out the occasional "roll initiative", that usually allows a DM to regain control

A group of friends will do this. No worries.

I think some of my sessions that end up being ~7 hours can drag on a little bit. Something I personally need to work on, maybe getting more involved with each character and keeping to the meat and potatoes of the story. I provide lots of lore and mystery in my campaign so them going on side quests to solve problems is not an issue. This is much harder to accommodate with adventure modules. Try shortening your sessions or taking breaks at the top of the hour.

Something I did was incorporate a river battle with a  cyclops and a falling bridge, while trying to save horses off a sinking ship. This was like the first part of the session, so afterwards everything else seemed boring. Try working towards a climax at every session.

Personally, I run into this problem a lot along with the problem of people speaking about something unrelated to the campaign while someone else is trying to do something in game. I feel the players knew just how bad it was in one of my campaigns and they decided as a group to begin raising their hands when they'd like to speak (and did this without telling me until they started raising their hands) and honestly, it's worked quite well. The players are on track and stay on track which is good (especially since we have short sessions that max out at 3 hours) and a lot of the tension caused from people being rude is gone. A similar, free spirited atmosphere remains (as players occasionally talk) but it's much more organized.

I'm not saying this is something that will work for everyone and I'm sure many people here don't like this idea (as I myself don't like the idea very much) but, with certain groups, it can work miracles at not only keeping people focused and on track but also helps prevent them from trying to speak over each other.

All I have to say is that D&D is a cooperative storytelling experience so if your players enjoy these tangents them continue how you are playing now. If you all agreed that you'd rather not have them than all of you need to work together to lessen the amount of tangents the party goes on.

Some people have misunderstood the OP: it is not that the players are going on side quests or meandering in town. They are talking about things outside the game e.g. Netflix, how to cook a gumbo, whether they could ride a panda etc.

This is down to you as the DM to control, but that's not easy and you shouldn't feel bad. These are a group of friends socialising, and so sometimes these sidebars will occur. But since you've all discussed it, and everyone wants to play more of the game then I'd do the following:

1) I always allow 20-30 minutes at the start of a session for everyone to chat about their week and what they've been doing. Once you're caught up, sidebars are less likely.

2) Put in a fun, silly way of bringing talk back to the game. I suggest that you allow any of these sidebars to run for a couple of minutes, and if you think it's not relevant/important then put the palm of your hand on your forehead and wait. Everyone else also has to copy you when they see you doing it. When everyone has done so, they'll remember to get back to the game. Alternatively, just say "TANGENT!" and then everyone else has to do the same. It will probably become a fun in-joke and you won't be the only one responsible.

3) Do these things sparingly and judge whether someone actually really needs to talk about something. Don't say 'TANGENT!' when they're talking about how they're worried about their exams, or that their dog is sick for instance.

Hope this helps.