While there isn't a single "Facebook's #3 Secret" universally recognized for group growth, especially for targeting USA membership in 2024, the core strategies revolve around a few key principles that consistently deliver results. The search results highlight several important approaches.

Here's a breakdown of how to boost USA membership in your Facebook Group in 2024, combining effective strategies with insights from the search results, and highlighting a powerful, often overlooked aspect:

The Core Principle: Value and Engagement (The "Secret" is not a single trick, but consistent application of these)

Facebook's algorithm prioritizes groups with high engagement and meaningful interactions. To attract and retain US members, you need to provide consistent value and foster a thriving community. This isn't a secret per se, but rather the fundamental driver behind all successful group growth.

Key Strategies to Boost USA Membership:

Hyper-Targeted Content & Niche Focus:

Define Your Ideal USA Member: Go beyond basic demographics. What are their specific interests, pain points, hobbies, lifestyle, and even purchasing habits? (As mentioned in the search results, using Facebook's detailed targeting for ads, and understanding your existing US audience, is crucial).
Create Value-Driven Content: Focus on content that directly addresses the needs and interests of your target US audience. This could be:
Informative posts, tutorials, and guides relevant to their locale or concerns.
Polls, Q&As, and discussions that encourage participation.
Behind-the-scenes content or personal stories that build connection.
Exclusive resources, content, or opportunities available only to group members.
Geographic Specificity: If your group has a local focus, leverage that. Promote events or discussions relevant to specific US cities or regions.
Strategic Promotion & Visibility:

Leverage Facebook Ads (The most direct way to target US users):
Custom Audiences: Upload customer lists (emails, phone numbers) or create custom audiences based on website visitors to reach people already familiar with your brand in the US.
Lookalike Audiences: Create Lookalike Audiences based on your existing US customers or highly engaged members. Facebook's machine learning will find similar users in the US who are likely to join your group.
Detailed Targeting: Utilize Facebook's detailed targeting options (demographics, interests, behaviors) to reach specific segments of the US population who would be interested in your group.
Clear Call to Action (CTA): Ensure your ads have a compelling and clear CTA to join your group.
Cross-Promotion:
Your Facebook Page: Promote your group heavily on your associated Facebook Page.
Other Social Media Platforms: Share links to your group on Instagram, YouTube, TikTok, LinkedIn, etc., especially if you have a US following on those platforms.
Website/Email List: Embed links to your group on your website, in blog posts, and in your email newsletters.
Collaborate with US-based Micro-Influencers: Partner with influencers who have an engaged US audience relevant to your niche. Interviews, joint webinars, or mentions can drive significant traffic.
Engage in other relevant US-focused Groups: Participate actively in other established Facebook groups (where allowed and appropriate) by providing value and subtly directing people to your group if it's a good fit.
Community Building & Moderation (The "Secret" Sauce for Retention):

Active Moderation and Engagement: This is critical for any group, but especially for attracting and retaining US members.
Respond to comments and questions promptly.
Foster a welcoming and inclusive environment.
Remove spam and irrelevant content immediately. (As one search result notes, strict moderation is key).
Encourage member-generated content and discussions.
Recognize and Reward Engaged Members: Feature member spotlights, acknowledge contributions, and consider creating a "VIP" program for highly active US members.
Host Live Sessions & Events: Regular Facebook Live sessions (Q&As, workshops, interviews) create a dynamic and interactive environment that appeals to a US audience, fostering real-time engagement.
Set Clear Rules and Expectations: This helps maintain a positive and productive environment, which is attractive to members looking for a quality community.
The "Facebook's #3 Secret" (As suggested by some results): Leveraging Organic Reach within Groups through High Engagement and Niche Focus.

While the initial search for "Facebook's #3 Secret" didn't reveal a single, universally known "secret," several sources emphasize the power of organic reach within groups as a major growth driver. Facebook's algorithm prioritizes group content in user newsfeeds more than regular Page posts.

Therefore, the "secret" to boosting USA membership (and overall group growth) isn't a hidden trick, but rather the consistent and intentional application of the strategies above, with a strong emphasis on:

Creating genuinely engaging content that sparks conversation.
Fostering a strong sense of community.
Encouraging active participation from existing members.
When members are highly engaged, they are more likely to invite friends, and Facebook's algorithm is more likely to suggest your group to other relevant US users. This organic virality, fueled by genuine connection and value, is arguably the most powerful "secret" to sustainable group growth.